R1:44f2010a0b60

PhabricatorPhabricatorAuthProvider: Remove unnecessary Remarkup

Summary:
This is a small fix in a specific user message example. See other messages in the very same file which also use `<tt>`.

Here the problematic phrase:

{F292970}

See the example in the phrase "Use lowercase letters, digits, and periods. For example: ...".

Test Plan: After this change, the specific message "The URI where the OAuth server is installed. For example" from the page `/auth/config/edit/?