Reland "[test] Move timeout control to timeout processor"

This is a reland of 4de2be99.

Original change's description:
> [test] Move timeout control to timeout processor
>
> Bug: v8:6917
> Change-Id: I03be38be952f0d59eb20fa98102ef09ca795de40
> Reviewed-on: https://chromium-review.googlesource.com/883446
> Commit-Queue: Michał Majewski <majeski@google.com>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50848}

Bug: v8:6917
Change-Id: I7c83bf1cb8965a149b06c1dbc138b5d097f5275d
Reviewed-on: https://chromium-review.googlesource.com/883284Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Commit-Queue: Michał Majewski <majeski@google.com>
Cr-Commit-Position: refs/heads/master@{#50854}

tools/testrunner/num_fuzzer.py

@@ -123,6 +123,10 @@ class NumFuzzer(base_runner.BaseTestRunner):
     while options.fuzzer_random_seed == 0:
       options.fuzzer_random_seed = random.SystemRandom().randint(-2147483648,
                                                                  2147483647)
+
+    if options.total_timeout_sec:
+      options.tests_count = 0
+
     return True
 
   def _get_default_suite_names(self):