all: Enabled horizontal indexed search code path by default
Created by: keegancsmith
We now enabled the new horizontal indexed search by default. Even if you only have one replica (the default and usual case), this slightly changes the codepath we take when doing a search. Additionally, we now prefer the INDEXED_SEARCH_SERVERS environment variable and have deprecated the old environment variable (ZOEKT_HOST).
This commit also updates the default address to "indexed-search-0.indexed-search:6070". The old address won't be valid on k8s deployments from the next release.
Part of https://github.com/sourcegraph/sourcegraph/issues/5725