mysqldump gzip compression runs on a single thread, can lead to unexpected action timeouts

[Ksawery Dziekoński]

It was observed that the `mysqldump` action can take an extended period of time to gzip-compress a database dump, due to running on a single thread, which in certain circumstances could lead to unexpected timeouts.

[Ksawery Dziekoński (ksdziekonski)]

Proposed fix to branch `master` can be found for review at: https://review.opendev.org/c/openstack/charm-mysql-innodb-cluster/+/839573

[OpenStack Infra (hudson-openstack)]

Change abandoned by "James Page <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/charm-mysql-innodb-cluster/+/839573
Reason: This review is > 12 weeks without comment, and failed testing the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Alex Kavanagh (ajkavanagh)]

Note that there is a review (see #2) that can re resurrected to implement this feature, if it is still required.