Remove unused protoc_plugin Dockerfile (#1498)

Author: sampajano

README.md

@@ -92,6 +92,9 @@ sudo mv protoc-gen-grpc-web-2.0.0-darwin-aarch64 \
 chmod +x /usr/local/bin/protoc-gen-grpc-web
 ```
 
+Note: If you are using our Docker setup, the `prereqs` image already includes
+both `protoc` and the `protoc-gen-grpc-web` plugin on the PATH.
+
 ### (Optional) 4. Verify Installations
 
 You can optionally verify the plugins work by following our [Hello World example](https://github.com/grpc/grpc-web/tree/master/net/grpc/gateway/examples/helloworld#generating-stubs):

docker-compose.yml

@@ -93,13 +93,6 @@ services:
     image: grpcweb/interop-client
     ports:
       - "8081:8081"
-  protoc-plugin:
-    build:
-      context: ./
-      dockerfile: ./net/grpc/gateway/docker/protoc_plugin/Dockerfile
-    depends_on:
-      - prereqs
-    image: grpcweb/protoc-plugin
   jsunit-test:
     build:
       context: ./