Avoid scrolling when the search is open (#19775)

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 ✅

(cherry picked from commit 71409f84f7ac6ec94b55b6e00975467794e32ec0)
Service-Card-Id: PVTI_lADOAF3p4s4BBcTlzgkLCdk
Service-Version: 1.24