Prevent WikiMetrics from collecting metrics if db record already exists

[dati18]

Prevent WikiMetrics from collecting metrics if a record for today already exists in the database, as that would result in a primary key integrity constraint violation.

This should help reduce logs like this:

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '321_2026-01-01' for key 'PRIMARY'

Bug: T423554

[outdooracorn]

• Add a test that runs the UpdateWikiDailyMetricJob() twice to reproduc the test
• Add withoutOverlapping() to the job to prevent 2 runs at the same job from overlapping
• Add a check for existing records for this wiki/date to WikiMetrics.php

Bug: T423554

The current description gives an overview of what this PR does, which is useful but ultimately can likely be figured out by looking at the diff. What would be really useful to add to the description is why we are we making this change. What was the original context/issue? Why does this change achieve its goal? Etc.

P.S. there are also some typos in the description ;)

[outdooracorn]

This looks correct. However, I have some suggested improvements.

Also, the PR description still talks about the "schedule without overlapping" change that was removed from this PR.

I see you're on annual leave now, so I'll take over this PR.

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I think that another possible reason we are getting this "Integrity constraint violation" log spam is because the 'redis' queue has a retry_after of only 100 seconds but UpdateWikiDaiyMetricJob::$timeout is set to 1hr - meaning that the job can be retried by another queue worker before the job is expected to have finished or has been terminated. The API chart sets Horizon tries to 3 by default so jobs are retied by default. I think the ShouldBeUnique interface is only evaluated at dispatch time, not when a job is retried. I think Job Middleware is run so we could use the WithoutOverlapping middleware (not to be confused with Schedule::withoutOverlapping() which is named similarly but functions completely differently).

[outdooracorn]

Good to go from my side but I touched it last so will let someone else also approve.