[REF] Fix metadata label for contribution_page_id

[eileenmcnaughton]

Overview

Adds label for contribution_page_id to the html metadata & switches search to use this

Before

With just the xml change we get a label regression

After

By also fixing the metadata it continues to display correctly

Technical Details

@colemanw this is how we can use the existing metadata conventions to present the right labels in html without distorting the meaning of the field & making it unavailable for other purposes

Comments

[civibot]

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[eileenmcnaughton]

@colemanw can I get you to check this - this is using the html label rather than the title to render the html label - which allows the field title to be used as the field title.

[colemanw]

This is a clever solution. I think I like it.
Lots of fields to update now!

[seamuslee001]

Merging based on @colemanw +1

[eileenmcnaughton]

woot!