search: remove repo subset symbol search job
Created by: rvantonder
Stacked on https://github.com/sourcegraph/sourcegraph/pull/32538.
Removes the now unused symbol job.
Test plan
Semantics-preserving.
Created by: rvantonder
Stacked on https://github.com/sourcegraph/sourcegraph/pull/32538.
Removes the now unused symbol job.
Semantics-preserving.