fix: reduce CPU usage by refreshing langserver info less frequently
Created by: chrismwendt
This mitigates https://github.com/sourcegraph/enterprise/issues/13646 by refreshing language server info once every 5s instead of 1s. This makes language server info a bit more stale but reduces CPU usage by a lot (this was a hot spot while idle).
Fixes https://github.com/sourcegraph/enterprise/issues/13646
This PR does not need to update the CHANGELOG because it has a negligible effect on UX.