test_runner: filter execArgv fallback for child tests

Apply the test runner propagation filter to execArgv entries that are
not reported by the options binding. This prevents config-file and
test-runner flags from leaking into isolated child tests while still
preserving V8 flags.

Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
Assisted-by: openai:gpt-5.5

Author: trivikr

lib/internal/test_runner/runner.js

@@ -208,7 +208,7 @@ function getRunArgs(path, { forceExit,
   const nodeOptionsSet = new SafeSet(processNodeOptions);
   const unknownProcessExecArgv = ArrayPrototypeFilter(
     process.execArgv,
-    (arg) => !nodeOptionsSet.has(arg),
+    (arg, i, arr) => !nodeOptionsSet.has(arg) && filterExecArgv(arg, i, arr),
   );
   ArrayPrototypePushApply(runArgs, unknownProcessExecArgv);