Fix problems highlighting redirects

This fixes three redirect highlighting problems:
1.  The last redirect returned from Elasticsearch was highlighted
regardless of quality.
2.  Finding a redirect that contains characters that have html escapes
would cause warnings.
3.  Finding a redirect that is more than 100 characters would cause
warnings.

Also add regression tests for these behaviors and fix regression tests
so you can create pages with ampersands in the name.

Bug: 56940
Change-Id: I7d8cf20acf8fd37a19ef30e569835c7e8c231c11
Merge "Fix problems highlighting redirects"