Concurrent invocation of updateFieldConfigScheme on FieldConfigSchemeManager may result in IssueTypeScheme and PriorityScheme to revert to default

Issue Summary

Concurrent invocation of updateFieldConfigScheme on FieldConfigSchemeManager may cause a race condition which may result in IssueTypeScheme and PriorityScheme to revert to the default schemes.

Steps to Reproduce

1. create a project TestProject and assign a new IssueType and Priority scheme to this project
2. create a large number of projects (>500) using shared configuration from TestProject so that we have 500+ projects sharing the same configuration. Take care to create projects in a non-concurrent fashion (i.e. one-by-one) to not trigger the race condition.
3. create multiple new projects with the same shared configuration concurrently (in parallel).
4. notice that IssueTypeScheme and PriorityScheme for some projects may revert.

Since this is a race condition it may be possible to not trigger the behaviour described all the time so this may need a couple of trials. For recreation purposes, we can use a load testing tool like JMeter for steps (3) and (4) above. For (3) we set threadpool size to 1 to and for step (4) we set it to 5 with no ramp-up time so that we try to create 5 projects concurrently.

Expected Results

All new projects created and old projects have their schemes assigned to the schemes we've created at step (1)

Actual Results

For some projects, priority and/or issuetype schemes revert to default schemes.

Workaround

Performing issueTypeScheme and priorityScheme changes, or operations that may trigger such changes automatically, like creating a project using shared configuration in a non-concurrent fashion (i.e. not in parallel but one action at a time)

Note: this bug report looks similar to JRASERVER-66625, however, the execution path mentioned in this ticket (see steps to reproduce on this ticket) is already fixed and does not cause this issue.

Recovering the Issue Type Scheme associations

See JSWSERVER-20581 or JRASERVER-66625 for details how to recover Scheme associations