bug: mtr `main ` test fail suite

[zsp108]

Describe the problem

Mtr test fail suite :
main (group_concat_max_len warning need fix)
sys_vars
binlog
rpl
opt_trace
parts
query_rewrite_plugins
sysschema

Expected behavior

Completed: All * tests were successful.

How To Reproduce

./mtr --suite=main --force --max-test-fail=0 --retry=0 --parallel=10 > main.log
./mtr --suite=sys_vars --force --max-test-fail=0 --retry=0 --parallel=10 > sys_vars.log
./mtr --suite=binlog --force --max-test-fail=0 --retry=0 --parallel=10 > binlog.log
./mtr --suite=rpl --force --max-test-fail=0 --retry=0 --parallel=10 > rpl.log
./mtr --suite=opt_trace --force --max-test-fail=0 --retry=0 --parallel=10 > opt_trace.log
./mtr --suite=parts --force --max-test-fail=0 --retry=0 --parallel=10 > parts.log
./mtr --suite=query_rewrite_plugins --force --max-test-fail=0 --retry=0 --parallel=10 > query_rewrite_plugins.log
./mtr --suite=sysschema --force --max-test-fail=0 --retry=0 --parallel=10 > sysschema.log

Environment

../bin/mysqld  Ver 5.7.36-StoneDB for Linux on x86_64 (build-)
build information as follow:
        Repository address: https://github.com/zsp108/stonedb.git:test/mtr57
        Branch name: test/mtr57
        Last commit ID: a4f8e80
        Last commit time: Date:   Mon Aug 8 17:48:21 2022 +0800
        Build time: Date: Tue Aug  9 07:28:19 UTC 2022

Linux ub01 5.4.0-122-generic #138-Ubuntu SMP Wed Jun 22 15:00:31 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Are you interested in submitting a PR to solve the problem?

• Yes, I will!