build: use local core sdk across modules

scripts/update-all.sh

@@ -42,16 +42,13 @@ for module_dir in "${modules[@]}"; do
       go get -u ./...
     fi
     go mod tidy
+    # Keep the current parent module in every go.mod. This prevents older
+    # transitive gRPC requirements from selecting the pre-split 2019 module
+    # when a workspace module is built on its own.
+    go get google.golang.org/genproto@latest
   )
 done
 
-echo
-echo "==> Pinning the current genproto parent module for workspace compatibility"
-(
-  cd -- "${modules[0]}"
-  go get google.golang.org/genproto@latest
-)
-
 echo
 echo "==> Synchronizing go.work"
 go work sync