Revert "Include host and project in code-owners not enabled error."

This reverts commit 4d2728b03e.

Reason for revert: Won't work if gerrit=None

Original change's description:
> Include host and project in code-owners not enabled error.
>
> Bug: 329231688
> Change-Id: I36bb24f167854f40718ec49559d9aaa640fa1a44
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5384365
> Auto-Submit: Joanna Wang <jojwang@chromium.org>
> Commit-Queue: Joanna Wang <jojwang@chromium.org>
> Reviewed-by: Scott Lee <ddoman@chromium.org>
> Commit-Queue: Scott Lee <ddoman@chromium.org>

Bug: 329231688
Change-Id: I49d23611b62f1979578ae52861a2007a1d34778e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5381788
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Joanna Wang <jojwang@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

presubmit_canned_checks.py

@@ -1550,8 +1550,7 @@ def CheckOwnersFormat(input_api, output_api):
 
     return [
         output_api.PresubmitError(
-            f'code-owners is not enabled on {input_api.gerrit.host}/{input_api.gerrit.project}. '
-            'Ask your host enable it on your gerrit '
+            'code-owners is not enabled. Ask your host enable it on your gerrit '
             'host. Read more about code-owners at '
             'https://chromium-review.googlesource.com/'
             'plugins/code-owners/Documentation/index.html.')
@@ -1571,8 +1570,7 @@ def CheckOwners(input_api, output_api, source_file_filter=None, allow_tbr=True):
 
     return [
         output_api.PresubmitError(
-            f'code-owners is not enabled on {input_api.gerrit.host}/{input_api.gerrit.project}. '
-            'Ask your host enable it on your gerrit '
+            'code-owners is not enabled. Ask your host enable it on your gerrit '
             'host. Read more about code-owners at '
             'https://chromium-review.googlesource.com/'
             'plugins/code-owners/Documentation/index.html.')