Lock issues when clearing cache on Percona XtraDB cluster

CI failures for #11

Not sure if this is the fix to CI errors, but think it'll work...

This issue is being reviewed by the kind folks in Slack, #needs-review-queue-initiative. We are working to keep the size of Needs Review queue [2700+ issues] to around 400 (1 month or less), following Review a patch or merge request → as a guide.

This could use an issue summary update using the default issue template. What's the proposed solution? What's the remaining tasks? Example this will need a test case to show the issue

Reroll for D11.2 and up