style: use import repo_logging everywhere

Align with Google style guides and `import repo_logging` as a module
rather than import symbols out of it.

Change-Id: Ie13c1f13be00dbf6dd3814a8780baf6453972237
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/647823
Tested-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>
Reviewed-by: Brian Gan <brgan@google.com>

git_command.py

@@ -23,7 +23,7 @@ from typing import Any, Optional
 import error
 from git_trace2_event_log_base import BaseEventLog
 import platform_utils
-from repo_logging import RepoLogger
+import repo_logging
 import repo_trace
 from wrapper import Wrapper
 
@@ -40,7 +40,7 @@ GIT_ERROR_STDOUT_LINES = 1
 GIT_ERROR_STDERR_LINES = 10
 INVALID_GIT_EXIT_CODE = 126
 
-logger = RepoLogger(__file__)
+logger = repo_logging.RepoLogger(__file__)
 
 
 class _GitCall: