Gracefully skip mongo collection on non-readable replica states

[HadhemiDD]

What does this PR do?

Makes the mongo check tolerate replica-set nodes that are not in a readable (PRIMARY/SECONDARY) state instead of crashing.

When a monitored mongod is in a state that is neither PRIMARY(1) nor SECONDARY(2) — e.g. RECOVERING(3), STARTUP(0), STARTUP2(5), ROLLBACK(9), DOWN(8) — read commands fail with pymongo.errors.NotPrimaryError (code 13436, NotPrimaryOrSecondary). Since NotPrimaryError subclasses ConnectionFailure, it was caught by the check's CRITICAL_FAILURE handling, marking the whole instance CRITICAL and dumping a traceback even though the node is reachable.

Changes:

• Add a centralized ReplicaSetDeployment.is_readable property (replset_state in {PRIMARY, SECONDARY}).
• Replace the scattered replset_state == 3 guards in operation_samples.py, query_metrics.py, and discovery.py with is_readable, so all non-readable states are skipped (not just RECOVERING).
• Catch NotPrimaryError as a non-critical, transient condition in the synchronous collector loop (_collect_metrics) and at the check() level — the run is skipped and the service check stays OK instead of going CRITICAL.
• Add NotPrimaryError handling to the $queryStats read path, mirroring the existing handling in operation samples' $currentOp.

Motivation

Users running the check against a replica-set member that briefly enters a non-readable state (recovering, rollback, etc.) saw the whole check fail with a NotPrimaryError traceback and a CRITICAL service check, when the correct behavior is to skip collection for that run and recover automatically.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add qa/required if this PR needs QA validation, or qa/skip-qa if it does not. Exactly one of the two is required.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

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🚦 43 Pipeline jobs failed

PR | test / test (linux, ubuntu-22.04, mongo, MongoDB (py3.13-4.4-auth), py3.13-4.4-auth) / MongoDB (py3.13-4.4-auth)-py3.13-4.4-auth     

PR | test / test (linux, ubuntu-22.04, mongo, MongoDB (py3.13-4.4-shard), py3.13-4.4-shard) / MongoDB (py3.13-4.4-shard)-py3.13-4.4-shard     

PR | test / test (linux, ubuntu-22.04, mongo, MongoDB (py3.13-4.4-standalone), py3.13-4.4-standalone) / MongoDB (py3.13-4.4-standalone)-py3.13-4.4-standalone     

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