docs(tests): fix CommentChecker findings across tests/ — 13,392 → 0 (repo-wide scan clean)

Comment/XML-doc changes only:
- add summaries to ~10k test methods, fixtures, fakes and helpers
  (+ <param> on theories, <returns> on async Task methods,
  <inheritdoc/> on interface implementations the checker can resolve)
- strip ~2.6k project-tracking references (WP*, P*-*, row-NN, Task N,
  #NN, Component-0NN) from comments, keeping the explanatory text;
  reword false positives in comments only
- real docs on fakes implementing BCL/library interfaces
  (IDisposable, ILogger, IOptionsMonitor, IAsyncLifetime)
- reword the last 5 src/ false positives (CWE-1236, failures-1,
  year-0001, M365)

Only non-comment edits: four one-line nested classes split across lines
so members can carry docs. Build 0 errors / 0 warnings.

tests/ZB.MOM.WW.ScadaBridge.LoadHarness/Scenarios/StoreAndForwardDrainScenario.cs

@@ -49,7 +49,7 @@ public sealed record DrainProgressSample(double ElapsedSeconds, long Delivered,
 /// Phase 1 buffers <paramref name="messageCount"/> messages with
 /// <c>attemptImmediateDelivery: false</c>, spread across many origin instance names
 /// and issued from many concurrent tasks — the "concurrent buffering from multiple
-/// instances" WP-4 asks about (<c>[xc-7]</c>). Phase 2 registers a delivery handler
+/// instances" case the load test targets. Phase 2 registers a delivery handler
 /// that always succeeds and drives sweeps to completion, timing the drain.
 /// </para>
 /// <para>