chore: clear dead test and allowlist leftovers of dropped runtimes

tests/msd-agent-isolation-guard.test.cjs

@@ -1289,8 +1289,7 @@ describe('#3045 MAJOR — --harness-flag can now accept a bare CLI-flag value (C
     // fabricated registry precondition), not a production defect — corrected
     // here to prove the `--harness-flag=<value>` parser generalizes to any
     // bare-CLI-flag-shaped value, not merely Cursor's specific '--worktree'
-    // string (which the sub-test above already pins). (Originally pinned on
-    // windsurf, retired in prune-runtimes.)
+    // string (which the sub-test above already pins).
     assert.equal(
       runtimes.zcode.runtime.harnessIsolationFlag,
       undefined,