Flaky TestMySQLShellBackupEngine_ExecuteBackup_ReleaseLock

[rohit-nayak-ps]

Overview of the Issue

This has been failing very often in unit test:
https://github.com/vitessio/vitess/actions/runs/12216802647/attempts/1#summary-34080298457

  TestMySQLShellBackupEngine_ExecuteBackup_ReleaseLock/lock_released_if_we_see_the_mysqlsh_lock_being_acquired: vitess.io/vitess/go/vt/mysqlctl
Failed
     mysqlshellbackupengine_test.go:379: 
        	Error Trace:	/home/runner/work/vitess/vitess/go/vt/mysqlctl/mysqlshellbackupengine_test.go:379
        	Error:      	"I1207 23:10:52.979759 mysqlshellbackupengine.go:117] Starting ExecuteBackup in test\nI1207 23:10:52.980004 mysqlshellbackupengine.go:150] acquiring a global read lock before fetching the executed GTID sets\nI1207 23:10:52.980032 mysqlshellbackupengine.go:169] running /tmp/TestMySQLShellBackupEngine_ExecuteBackup_ReleaseLock2161611042/001/test.sh --defaults-file=/dev/null --js -h localhost -e util.dumpInstance(\"logical/tmp/TestMySQLShellBackupEngine_ExecuteBackup_ReleaseLocklock_released_if_we_see_the_mysqlsh_lock_being_acquired1404449886/001\", {\"threads\": 4})\nW1207 23:10:52.988420 backup.go:524] error scanning lines from mysqlshell stderr: io: read/write on closed pipe\nE1207 23:10:52.988460 mysqlshellbackupengine.go:534] could not release global lock earlier\nI1207 23:10:52.988479 mysqlshellbackupengine.go:203] Writing backup MANIFEST\nI1207 23:10:52.988910 mysqlshellbackupengine.go:243] Backup completed\nI1207 23:10:52.988919 xtrabackupengine.go:161] Closing backup file MANIFEST\n" does not contain "global read lock released after"
        	Test:       	TestMySQLShellBackupEngine_ExecuteBackup_ReleaseLock/lock_released_if_we_see_the_mysqlsh_lock_being_acquired
        	Messages:   	failed to release the global lock after mysqlsh