When text scrolls in and out of view, depending on the length
of the scrollback and latency of input, `GetSearchHighlightFocused`
would change which would trigger a `ScrollToSearchHighlight` call.
This PR changes the behavior such that only actively changing the
search mask triggers a search (typing text or pressing enter).
Closes#19754
## Validation Steps Performed
* Brining text in and out of view doesn't scroll ✅
* Toggling the aA button scrolls results into view ✅