InnoDB fails to write MLOG_INDEX_LOAD upon completing ALTER TABLE

While testing the fix of MDEV-12699, it became clear that crash recovery of ROW_FORMAT=COMPRESSED tables is broken. If I remember correctly, an assertion would fail while applying the MLOG_COMP_REC_INSERT record.

To repeat this more easily, we should probably try to reduce the page flushing rate, or simply remove the workarounds for this bug in the MDEV-12669 fix.

mleich, please try to find a small case for this, either with or without mariabackup. For 10.2, please use innodb_log_optimize_ddl=OFF if the test involves any CREATE INDEX or table-rebuilding ALTER TABLE.