fix: exclude provisioner_state from workspace_build_with_user view (#22159)

The provisioner state for a workspace build was being loaded for every
long-lived agent rpc connection. Since this state can be anywhere from
kilobytes to megabytes this can gradually cause the `coderd` memory
footprint to grow over time. It's also a lot of unnecessary allocations
for every query that fetches a workspace build since only a few callers
ever actually reference the provisioner state.

This PR removes it from the returned workspace build and adds a query to
fetch the provisioner state explicitly.

coderd/rbac/authz.go

@@ -81,6 +81,7 @@ const (
 	SubjectAibridged                        SubjectType = "aibridged"
 	SubjectTypeDBPurge                      SubjectType = "dbpurge"
 	SubjectTypeBoundaryUsageTracker         SubjectType = "boundary_usage_tracker"
+	SubjectTypeWorkspaceBuilder             SubjectType = "workspace_builder"
 )
 
 const (