[OsSettings] Update owners for os settings strings

There is a bug in caching logic as since this file is evaluated before
OWNERS file in os_settings_strings_grdp folder, thus presubmit failed.

Making regex strings more specific to only apply to .grdp files.
This doesn't affect other settings strings folders because they all
have their OWNERS file.

Bug: 1131197
Change-Id: I81abecaf2600756de12ed847fa8be5325c16d36c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2430525Reviewed-by: Greg Thompson <grt@chromium.org>
Commit-Queue: My Nguyen <myy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810500}

chrome/app/OWNERS

@@ -35,7 +35,7 @@ per-file printing_strings.grdp=file://printing/OWNERS
 
 per-file profiles_strings.grdp=file://chrome/browser/profiles/OWNERS
 
-per-file *settings*strings*=file://chrome/browser/resources/settings/OWNERS
+per-file *settings*strings*.grdp=file://chrome/browser/resources/settings/OWNERS
 
 per-file supervised_user_error_page_strings.grdp=file://chrome/browser/supervised_user/supervised_user_error_page/OWNERS