1. 1. What this PR does

Makes the delete-metric assertions in `jstests/noPassthrough/query/queryStats/query_stats_delete_cmd_metrics.js` robust to spurious `WriteConflictException`s on debug builds.

• Adds `retryDeleteMetricTestOnWriteConflict(ctxFn, testFn, maxAttempts = 5)` to `jstests/libs/query/query_stats_write_cmd_utils.js`. It resets the collection and query stats store, runs the caller's exact-metric assertion, and retries (up to `maxAttempts`) until an execution passes; if all attempts fail it rethrows the last error.
• Wraps the five replica-set delete-metric cases (`single`, `_id`, `multi`, `no matches`, `partial success`) in that helper.

The `docsExamined` expectations stay exact, and the sharded path is untouched.

1. 1. Motivation

The test asserts `docsExamined` exactly. On debug builds a spurious `WriteConflictException` re-runs the delete's COLLSCAN, nondeterministically inflating `docsExamined` above its true value (e.g. an expected sum of 8 was recorded as 11), causing a rare one-off failure.

Per-op accounting was ruled out: the operation's `writeConflicts` counter does not track these command-level retries (observed 3 conflicts producing 14 extra examinations, and a run with 16 examined but 0 recorded conflicts), so the count cannot be corrected arithmetically. Retrying until a clean execution keeps the assertions exact — a genuine regression produces the wrong value on every attempt and still fails once retries are exhausted.

1. 1. Reviewer reading guide

• Start with `jstests/libs/query/query_stats_write_cmd_utils.js` for the new `retryDeleteMetricTestOnWriteConflict` helper.
• Then `jstests/noPassthrough/query/queryStats/query_stats_delete_cmd_metrics.js` — the five replica-set `it()` bodies now call the helper; the metric expectations are unchanged.

1. 1. Caveats

• Only the replica-set delete cases are wrapped; the sharded suite uses a different fixture and its own `docsExamined` tolerance and is left as-is.
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