test(mysql): drop run_tests.sh mysql/ subdir entry after move

The mysql unittests now live in test/ and match the existing
brpc*unittest glob in run_tests.sh, so revert the script to master. The
removed mysql/brpc*unittest entry needed `shopt -s nullglob` to skip a
missing subdir, but CI runs the script under `sh` (dash), where shopt is
absent; nullglob stayed off and the now-empty glob was executed as a
literal path, exiting 127.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: rajvarun77

test/run_tests.sh

@@ -22,10 +22,7 @@ rm core.*
 test_num=0
 failed_test=""
 rc=0
-# nullglob so mysql/brpc*unittest expands to nothing (not a literal bogus
-# binary name) when that subdir was not built.
-shopt -s nullglob
-test_bins="test_butil test_bvar bthread*unittest brpc*unittest mysql/brpc*unittest"
+test_bins="test_butil test_bvar bthread*unittest brpc*unittest"
 for test_bin in $test_bins; do
     test_num=$((test_num + 1))
     >&2 echo "[runtest] $test_bin"