set verbose=False for mirror.populate in _UpdateMirrorIfNotContains()

In https://crrev.com/c/6442501, apply_patch_ref() was updated to
refresh the git cache when applying patches in gclient. However,
it causes an excessive number of logs to be created, particularly
for src/v8, as the repo has a huge number of branches.

This CL simply sets the verbose option with False,
ignoring the value in options.verbose.

Bug: 407795715
Change-Id: Ibf32ff67d23f41b398cca82372c17d7ca331db26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6486489
Commit-Queue: Scott Lee <ddoman@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

gclient_scm.py

@@ -1349,7 +1349,7 @@ class GitWrapper(SCMWrapper):
             depth = 10000
         else:
             depth = None
-        mirror.populate(verbose=options.verbose,
+        mirror.populate(verbose=False,
                         bootstrap=not getattr(options, 'no_bootstrap', False),
                         depth=depth,
                         lock_timeout=getattr(options, 'lock_timeout', 0))