release-22.1: spanconfig: reset job run_stats to avoid job system backoff

[blathers-crl]

Backport 1/1 commits from #82724 on behalf of @stevendanna.

/cc @cockroachdb/release

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If the coordinator of the span configuration job dies, another node
will adopt the job. However, when doing so it will bump the num_runs
run stat. As this number increases, the job system will delay future
resumptions of this job.

We solve this here by resetting the job's run_stats at the beginning
of the job.

We've yet again handled this in the job directly rather than adjusting
the behavior of the job system. In this case, my justification is that
this solution is fit for backporting.

Fixes #82689

Release note (bug fix): Fix a bug where the startup of an internal
component after a server restart could result in the delayed
application of zone configuration.

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Release justification: high impact bug fix that prevents the spanconfig job from being paused for long periods of time, resulting in no reconciliation

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[cockroach-teamcity]

This change is 

[adityamaru]

Merging on behalf of @stevendanna