Replace plugin.log with file_hook.log

File hooks feature was previously named plugins. We update an old log file
name to match new feature name.

Changelog: changed

doc/administration/file_hooks.md

@@ -63,8 +63,11 @@ need to restart GitLab to apply a new file hook.
 If a file hook executes with non-zero exit code or GitLab fails to execute it, a
 message is logged to:
 
-- `gitlab-rails/plugin.log` in an Omnibus installation.
-- `log/plugin.log` in a source installation.
+- `gitlab-rails/file_hook.log` in an Omnibus installation.
+- `log/file_hook.log` in a source installation.
+
+NOTE:
+Before 14.0 release, the file name was `plugin.log`
 
 ## Creating file hooks
 

lib/gitlab/file_hook_logger.rb

@@ -3,7 +3,7 @@
 module Gitlab
   class FileHookLogger < Gitlab::Logger
     def self.file_name_noext
-      'plugin'
+      'file_hook'
     end
   end
 end