style: use import event_log everywhere

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

Change-Id: I2c558f1161490b354f0b956ac0e86e658942c3a2
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/654813
Reviewed-by: Brian Gan <brgan@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

command.py

@@ -20,7 +20,7 @@ import re
 from typing import List, Optional, TYPE_CHECKING
 
 import error
-from event_log import EventLog
+import event_log
 import progress
 
 
@@ -57,7 +57,7 @@ class Command:
     # provide event summary to callers. Only used by sync subcommand currently.
     #
     # NB: This is being replaced by git trace2 events. See git_trace2_event_log.
-    event_log = EventLog(enabled=False)
+    event_log = event_log.EventLog(enabled=False)
 
     # Whether this command is a "common" one, i.e. whether the user would
     # commonly use it or it's a more uncommon command. This is used by the help