simplify check for existingTag
simplify check for existingTag

The existing tag messaging should not be dependent on selectedProfile.
Furthermore, the existing tag found should never be the same as the admin trackingID as this belongs to Google. This may have been needed before because the fetch request for `tagverify` was making an authenticated request.

google/site-kit-wp,google/site-kit-wp,google/site-kit-wp,google/site-kit-wp