with help of Serg and Elena guideline for fixing was formulated like this (should be moved in docs)
WAIT/NOWAIT clause of the command should not affect system tables opened implicitly because of internals of the sever implementation (like statistic, routine descriptions, logs and privileges), but affect tables inherited from tables/functions listed in the command (like underlying tables of views, triggers, functions)
diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
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index f27da375562..78a801951b1 100644
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--- a/sql/sql_statistics.cc
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+++ b/sql/sql_statistics.cc
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@@ -3210,6 +3210,8 @@ int read_statistics_for_tables(THD *thd, TABLE_LIST *tables)
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if (open_stat_tables(thd, stat_tables, &open_tables_backup, FALSE))
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DBUG_RETURN(1);
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+ DEBUG_SYNC(thd, "statistics_read_opened_tables");
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+
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for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
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{
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TABLE_SHARE *table_share;
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--source include/have_debug_sync.inc
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create table t1 (a int);
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insert into t1 values (1),(2),(3),(4);
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create table t2 (a int);
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insert into t2 values (1),(2),(3),(4);
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set @save_use_stat_tables= @@global.use_stat_tables;
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set session use_stat_tables= preferably;
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set global use_stat_tables= preferably;
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ANALYZE TABLE t1,t2 PERSISTENT FOR ALL;
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connect (con2,localhost,root,,);
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SET DEBUG_SYNC='statistics_read_opened_tables SIGNAL ready WAIT_FOR go';
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--send select * from t1
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--connection default
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SET DEBUG_SYNC="now WAIT_FOR ready";
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drop table t2 NOWAIT;
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SET DEBUG_SYNC="now SIGNAL go";
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select 1;
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--connection con2
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--reap
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--connection default
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SET DEBUG_SYNC='RESET';
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select * from mysql.table_stats;
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show tables;
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drop table t1;
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set session use_stat_tables= @save_use_stat_tables;
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set global use_stat_tables= @save_use_stat_tables;
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Here is the code which shows the problem: at the end the t2 table is deleted but statistics about it present.
Fixed test case which will work even with waiting for stat_tables
set global use_stat_tables= preferably;
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ANALYZE TABLE t1,t2 PERSISTENT FOR ALL;
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connect (con3,localhost,root,,);
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connect (con2,localhost,root,,);
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SET DEBUG_SYNC='statistics_read_opened_tables SIGNAL ready WAIT_FOR go';
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--send select * from t1
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--connection default
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SET DEBUG_SYNC="now WAIT_FOR ready";
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--send drop table t2 NOWAIT
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--connection con3
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select sleep(0.1);
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SET DEBUG_SYNC="now SIGNAL go";
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--connection con2
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--reap
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--connection default
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--reap
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--disconnect con2
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--disconnect con3
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SET DEBUG_SYNC='RESET';
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select * from mysql.table_stats;
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show tables;
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drop table t1;
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set session use_stat_tables= @save_use_stat_tables;
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set global use_stat_tables= @save_use_stat_tables;
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After talking to Serg, it should be implemented as handler calls table->file->extra(HA_EXTRA_SKIP_LOCKED) and table->file->extra_opt(HA_EXTRA_LOCK_WAIT, value).
Remove TL_READ_SKIP_LOCKED and TL_WRITE_SKIP_LOCKED 