remove reference to swarming_client

Python client is deprecated.

Bug: chromium:984869
Change-Id: I6b8f959d3c7d2de0d214cd07aeabfbf54c35c53b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/229960
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Takuto Ikuta <tikuta@google.com>
Cr-Commit-Position: refs/heads/main@{#34834}

DEPS

@@ -272,8 +272,6 @@ deps = {
   },
   'src/tools':
     'https://chromium.googlesource.com/chromium/src/tools@7fedcd5492f8cab7e7dda3389985625894d0071a',
-  'src/tools/swarming_client':
-    'https://chromium.googlesource.com/infra/luci/client-py.git@a32a1607f6093d338f756c7e7c7b4333b0c50c9c',
 
   'src/third_party/accessibility_test_framework': {
       'packages': [

tools_webrtc/mb/mb.py

@@ -364,12 +364,7 @@ class MetaBuildWrapper(object):
       if out:
         self.Print(out, end='')
       if err:
-        # The swarming client will return an exit code of 2 (via
-        # argparse.ArgumentParser.error()) and print a message to indicate
-        # that auth failed, so we have to parse the message to check.
-        if (ret == 2 and 'Please login to' in err):
-          err = err.replace(' auth.py', ' tools/swarming_client/auth.py')
-          self.Print(err, end='', file=sys.stderr)
+        self.Print(err, end='', file=sys.stderr)
 
       return ret