chromeos: Make additional args to the sanity test non-fatal.

It currently breaks the with/without patch retry flow:
https://ci.chromium.org/p/chromium/builders/try/chromeos-kevin-rel/820
https://chromium-swarm.appspot.com/task?d=true&id=46179d96935c9210

So let's ignore any --test-launcher-* args. The sanity tests is quick
and (hopefully) non-flaky enough to not need any of those.

R=jbudorick

Change-Id: I577508a63eaa6dbed3a248301bc0e39a8c19bcc7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1707048Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#678346}

build/chromeos/test_runner.py

@@ -564,9 +564,9 @@ class BrowserSanityTest(RemoteTest):
               '--gtest_repeat')]
 
     if self._additional_args:
-      raise TestFormatError(
-          'Sanity test should not have additional args: %s' % (
-              self._additional_args))
+      logging.error(
+          'Sanity test should not have additional args: These will be '
+          'ignored: %s', self._additional_args)
 
     # VMs don't have the disk space for an unstripped version of Chrome
     # instrumented for code coverage, so only strip in that case.