Add more tracing to git cache.

Change-Id: Iad21c3fa60f563f479ad0a0cadcfd8c1beb2fcc0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1881910
Auto-Submit: Erik Chen <erikchen@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@google.com>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>

git_cache.py

@@ -555,8 +555,10 @@ class Mirror(object):
         env = os.environ.copy()
         env.update({
             'GIT_TRACE_PACKET': '1',
-            'GIT_TRACE_PERFORMANCE': '1',
-            'GIT_TRACE_SETUP': '1'
+            'GIT_TR2_EVENT': '1',
+            'GIT_TRACE2_EVENT': '1',
+            'GIT_TRACE_CURL': '1',
+            'GIT_TRACE_CURL_NO_DATA': '1'
         })
         # Only print first 30000 packets. We can use nonlocal keyword once we
         # switch to python 3.