Correct AllowCrossOriginAuthPrompt policy caption

This policy controls the ability of cross-site images to trigger auth
prompts when a page is loaded. The policy applies only to images, and
applies to all HTTP authentication types (Basic/Digest/NTLM/Negotiate).
This CL updates the policy caption for accuracy.

Bug: 1124044
Change-Id: I6b6c06f3c73e524583262b623f0ea8ccd4ff5a92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2398893
Auto-Submit: Eric Lawrence [MSFT] <ericlaw@microsoft.com>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Commit-Queue: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805273}

components/policy/resources/policy_templates.json

@@ -4325,7 +4325,7 @@
       },
       'example_value': False,
       'id': 89,
-      'caption': '''Cross-origin HTTP Basic Auth prompts''',
+      'caption': '''Cross-origin HTTP Authentication prompts''',
       'tags': ['website-sharing'],
       'desc': '''Setting the policy to Enabled allows third-party images on a page to show an authentication prompt.