Deprecate existing service center search

[curtismchale]

Currently the top bar search is powered by Angular and the WP REST API but that sometimes means that the Angular app returns results slow while the WP Search and site are working fine.

We should remove the existing search in the top bar and move to only using WP Search. We are currently limited on who can work on the search as its bound up in an Angular app so moving it into WP will open up the ability for more people to work on it while reducing our tech stack.