Updates to gRPC generation (#3483)

Some cleanup post the last series of gRPC updates and changes for future
gRPC updates.

* Cleanup the instructions for better clarity and operational ordering.
* Fix for allocation gRPC generation to reuse the gRPC version include
in the build container image rather than unnecessarily build its own.

.github/ISSUE_TEMPLATE/kubernetes_update.md

@@ -38,10 +38,12 @@ List of items to do for upgrading to {version_1} {version_2} {version_3}
         - [ ] `dev_eks_example_cluster_version`, which is the newest EKS supported version in {version_1} {version_2} {version_3}
         - [ ] `dev_minikube_example_cluster_version`, which is {version_2} with the supported patch version
 - [ ] If client-go pulled in a new version of gRPC, then also
-    - [ ] Update the SDK [base image grpc version](https://github.com/googleforgames/agones/blob/main/build/includes/sdk.mk#L30) and rebuild the image. Note that this can take a while and in the past we have had to manually push it to gcr because cloud build doesn't like how long it takes.
-    - [ ] Regenerate allocated API endpoints: [make gen-allocation-grpc](https://github.com/googleforgames/agones/blob/main/build/includes/allocation.mk#L55)
-    - [ ] Regenerate all client sdks: [make gen-all-sdk-grpc](https://github.com/googleforgames/agones/blob/main/build/README.md#make-gen-all-sdk-grpc)
-    - [ ] Update the version number in C++ Cmake scripts [here](https://github.com/googleforgames/agones/blob/main/sdks/cpp/CMakeLists.txt#L100) and [here](https://github.com/googleforgames/agones/blob/main/sdks/cpp/cmake/prerequisites.cmake#L34)
+    - [ ] Update the `grpc_release_tag` in the SDK [base image grpc version](https://github.com/googleforgames/agones/blob/main/build/includes/sdk.mk).
+    - [ ] Update the gRPC version number in C++ CMake scripts, `AGONES_GRPC_VERSION` [here](https://github.com/googleforgames/agones/blob/main/sdks/cpp/CMakeLists.txt)
+          and `gRPC_GIT_TAG` [here](https://github.com/googleforgames/agones/blob/main/sdks/cpp/cmake/prerequisites.cmake)
+    - [ ] Regenerate all client sdks: [make gen-all-sdk-grpc](https://github.com/googleforgames/agones/blob/main/build/README.md#make-gen-all-sdk-grpc) 
+          This can take an hour or so, as the above changes force a rebuild. Plan your day accordingly 😃.
+    - [ ] Regenerate allocated API endpoints: [make gen-allocation-grpc](https://github.com/googleforgames/agones/blob/main/build/README.md#make-gen-allocation-grpc)
 - [ ] Confirm the update works as expected by running e2e tests
     - [ ] Add the new supported Kubernetes versions to the e2e clusters creation
         - [ ] In `terraform/e2e/module.tf`, add the new supported version to the map `kubernetes_versions`. Noted the location of the new clusters should have enough quota (CPU, In-use IP addresses) to create the cluster. And the new supported version is usually only available in RAPID channel.

build/includes/allocation.mk

@@ -20,9 +20,6 @@
 #   \__, |_| \_\_|    \____|   |_|\___/ \___/|_|_|_| |_|\__, |	
 #   |___/                                               |___/ 
 
-build_base_version = $(call sha,$(build_path)/build-sdk-images/tool/base/Dockerfile)
-build_base_tag = agones-build-allocation-base:$(build_base_version)
-
 # Calculate sha hash of sha hashes of all files in a specified ALLOCATION_FOLDER
 allocation_build_folder = build-allocation-images/
 sdk_build_folder = build-sdk-images
@@ -33,23 +30,14 @@ ALLOCATION_IMAGE_TAG=$(build_allocation_prefix)$(ALLOCATION_FOLDER):$(build_allo
 
 .PHONY: gen-allocation-grpc 
 
-# Builds the base GRPC docker image.
-build-build-image-base: DOCKER_BUILD_ARGS= --build-arg GRPC_RELEASE_TAG=$(grpc_release_tag)
-build-build-image-base: 
-	docker build --tag=$(build_base_tag) $(build_path)$(sdk_build_folder)/tool/base $(DOCKER_BUILD_ARGS)
-
-# create the GRPC base build image if it doesn't exist
-ensure-build-image-base:
-	$(MAKE) ensure-image IMAGE_TAG=$(build_base_tag) BUILD_TARGET=build-build-image-base
-
 # create the build image allocation if it doesn't exist
 ensure-build-allocation-image:
 	$(MAKE) ensure-image IMAGE_TAG=$(ALLOCATION_IMAGE_TAG) BUILD_TARGET=build-build-allocation-image ALLOCATION_FOLDER=$(ALLOCATION_FOLDER)
 
 # Builds the docker image
 # Note: allocation and sdk use the same dockerfile
-build-build-allocation-image: ensure-build-image-base
-	docker build --tag=$(ALLOCATION_IMAGE_TAG) --build-arg BASE_IMAGE=$(build_base_tag) -f $(build_path)$(sdk_build_folder)/$(ALLOCATION_FOLDER)/Dockerfile $(build_path)$(allocation_build_folder)$(ALLOCATION_FOLDER)
+build-build-allocation-image: ensure-build-sdk-image-base
+	docker build --tag=$(ALLOCATION_IMAGE_TAG) --build-arg BASE_IMAGE=$(build_sdk_base_tag) -f $(build_path)$(sdk_build_folder)/$(ALLOCATION_FOLDER)/Dockerfile $(build_path)$(allocation_build_folder)$(ALLOCATION_FOLDER)
 
 # Generates grpc server and client for a single allocation, use ALLOCATION_FOLDER variable to specify the allocation folder.
 gen-allocation-grpc: