Stop setting git config protocol.version

Git has been using version 2 of their wire protocol by default since
2.26, released in 2020. Stop setting it explicitely.

Change-Id: Ibc93a672b41c5a8183bc3200c506006f6e08af94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6070782
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

bootstrap/bootstrap.py

@@ -42,7 +42,6 @@ GIT_GLOBAL_CONFIG = {
     'core.filemode': 'false',
     'core.preloadindex': 'true',
     'core.fscache': 'true',
-    'protocol.version': '2',
 }
 # Version of GIT_GLOBAL_CONFIG above.
 GIT_POSTPROCESS_VERSION = '2'