[test] Make pool abort of test runner more robust

Bug: v8:9098
Change-Id: I8200b60605228e6974cd76443ad9d2f93bff56ba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2061552Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66307}

tools/testrunner/local/pool.py

@@ -196,7 +196,7 @@ class Pool():
             # gracefully, e.g. missing test files.
             internal_error = True
             continue
-
+          finally:
             if self.abort_now:
               # SIGINT, SIGTERM or internal hard timeout.
               return