The sample MTR calls

./mysql-test-run.pl  --mysqld=--innodb_random_read_ahead=ON innodb.create-index

./mysql-test-run.pl  --mysqld=--innodb_flush_sync=0 innodb.create-index

end up in

Logging: ./mysql-test-run.pl  --mysqld=--innodb_flush_sync=0 innodb.create-index

vardir: /home/mleich/Server_bin/10.5_asan_Og/mysql-test/var

Checking leftover processes...

Removing old var directory...

 - WARNING: Using the 'mysql-test/var' symlink

Creating var directory '/home/mleich/Server_bin/10.5_asan_Og/mysql-test/var'...

Checking supported features...

MariaDB Version 10.5.7-MariaDB-debug

 - SSL connections supported

 - binaries are debug compiled

 - binaries built with wsrep patch

Collecting tests...

Installing system database...

and than happens nothing extra == The process does not finish.

origin/10.5 440d4b282dd4992d64abdd6289859598db7e5f75 2020-11-02

origin/10.2 97f3207cf3d1a119fe3d6a56b204e5bf30cec109 2020-11-03   (10.2.35)

origin/10.3 2391582ec3f87378581fc5a55266b3d7c6c823d6 2020-11-03 (10.3.26)

origin/10.4 5739c7702d83e83ecff5cdd84e0fab899101f9f5 2020-11-03 (10.4.17)

have no problem with --innodb_flush_sync=0 or innodb_random_read_ahead=ON

IMHO the server process should either

a) not freeze if meeting these two settings during bootstrap (my preference)

  ... ignore them or fix whatever ...

or

b) print an error message telling that these settings are not supported during

    bootstrap and abort.

In case b) is picked and both options are important than some adjustment of MTR

could be made.