The initial implementation of the CMake parameter WITH_DBUG_TRACE allows some of the DBUG trace output to be disabled while leaving other important DBUG functionality intact - things like DBUG_ASSERT, DBUG_EXECUTE_IF.
This patch however was incomplete - it disabled DBUG_ENTER and DBUG_RETURN however left DBUG_PRINT in place.
It turns out that only a small number of InnoDB redo log related tests were making use of DEBUG_DBUG='+d,ib_log' to check that some log records were written or parsed. We can live very well without those checks.
Conditional branches are bad for tools like the rr debugger. Even if all DBUG_PRINT statements are normally disabled in test runs, the conditional branches would create unnecessary (and useless) opportunity of context switches in rr. I have witnessed a case where a test that would take more than 2 hours to run would finish in a few seconds when the server was compiled with cmake -DPLUGIN_PERFSCHEMA=NO -DWITH_DBUG_TRACE=OFF -DWITH_SAFEMALLOC=OFF.