Remove windows specific git pack limit

This is full version of
https://chromium-review.googlesource.com/823544

After the CL landing, we see no performance regression in bot_update step.
And regular 95%ile in 1h window improved from more than 300s to less than or around 200s.
See tandrii's query in https://bugs.chromium.org/p/chromium/issues/detail?id=749709#c91 for detail.

Let me reduce frequency of slow bot_update step more like below.
https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/69844
https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/69886
https://ci.chromium.org/buildbot/tryserver.chromium.win/win7_chromium_rel_ng/69892

Bug: 749709
Change-Id: I44474aa9ecdd733d68fd13fe8b791820fb80381f
Reviewed-on: https://chromium-review.googlesource.com/838766
Commit-Queue: Takuto Ikuta <tikuta@google.com>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>

git_cache.py

@@ -27,10 +27,6 @@ import subcommand
 # Analogous to gc.autopacklimit git config.
 GC_AUTOPACKLIMIT = 50
 
-# TODO(tikuta): remove or revert this (crbug.com/749709)
-if sys.platform.startswith('win'):
-  GC_AUTOPACKLIMIT = 30
-
 GIT_CACHE_CORRUPT_MESSAGE = 'WARNING: The Git cache is corrupt.'
 
 try:

recipes/recipe_modules/bot_update/api.py

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+
 """Recipe module to ensure a checkout is consistent on a bot."""
 
 from recipe_engine import recipe_api