Add match arm for unused builtin resource managers

Although we don't currently handle these, they are much different from
an unrecognized resource manager, which the comment in the last match
arm refers to.

control_plane/src/endpoint.rs

@@ -504,7 +504,7 @@ impl Endpoint {
     /// Map safekeepers ids to the actual connection strings.
     fn build_safekeepers_connstrs(&self, sk_ids: Vec<NodeId>) -> Result<Vec<String>> {
         let mut safekeeper_connstrings = Vec::new();
-        if self.mode == ComputeMode::Primary {
+        if matches!(self.mode, ComputeMode::Primary | ComputeMode::Upgrade) {
             for sk_id in sk_ids {
                 let sk = self
                     .env