Remove OOB deprecation log from gsutil

This change removes OOB deprecation log from gsutil. This is no longer necessary and it hinders with tools that use gsutil.py.

R=sokcevic, jojwang

Bug: 1412249, 1359383
Change-Id: If47239520a15d24658314bd44570babf99831e36
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4221926
Auto-Submit: Aravind Vasudevan <aravindvasudev@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

gsutil.py

@@ -187,9 +187,6 @@ def luci_login():
 
 def _luci_auth_cmd(luci_cmd, wrapped_cmds=None, interactive=False):
   """Helper to call luci-auth command."""
-  print('Using luci-auth login since OOB is deprecated.')
-  print('Override luci-auth by setting `BOTO_CONFIG` in your env.\n')
-
   cmd = ['luci-auth', luci_cmd, '-scopes', ' '.join(LUCI_AUTH_SCOPES)]
   if wrapped_cmds:
     cmd += ['--'] + wrapped_cmds