Only sentences should end with periods

Currently, a lot of our description texts aren't complete sentences (which is fine) but still end with a period (which isn't). We should remove the periods from the end of strings that don't form complete sentences.

Example (from search_api.processor.schema.yml):

      label: 'Text/HTML that will be prepended to all occurrences of search keywords in highlighted text.'

This is no sentence (it lacks a preposition), so shouldn't end with a period.

To fix, probably just search for the regex \.['"] and review all occurences.
This won't find comments, but that's on purpose: comments should always form complete sentences, and I think they're fine already.