[MM-28303]: check if mmctl exists before checking on Github and reduce requests to Github (#15387)

Summary:
Every make call would ping Github to find out the mmctl version to download. Each check made 4 requests to Github. So every make execution resulted in 4 requests to Github. This leads to frequent rate-limit errors from Github.
In this PR we check for the mmctl version only if mmctl doesn't already exist. We also print a more helpful error message.
Reduce the number the number of requests to Github from 4 to 2.

Ticket Link:
https://mattermost.atlassian.net/browse/MM-28303

Makefile

@@ -124,9 +124,6 @@ else
 ALL_PACKAGES=$(TE_PACKAGES)
 endif
 
-# Decide what version of prebuilt binaries to download. This will use the release-* branch names or change to the latest.
-MMCTL_REL_TO_DOWNLOAD:=$(shell scripts/get_latest_release.sh 'mattermost/mmctl' 'release-')
-
 all: run ## Alias for 'run'.
 
 -include config.override.mk
@@ -198,24 +195,15 @@ prepackaged-plugins: ## Populate the prepackaged-plugins directory
 	done
 
 prepackaged-binaries: ## Populate the prepackaged-binaries to the bin directory
-ifeq ($(MMCTL_REL_TO_DOWNLOAD),)
-	@echo "An error has occured trying to get the latest mmctl release. Aborting. Perhaps api.github.com is down?"
-	@exit 1
-endif
-# Externally built binaries
 ifeq ($(shell test -f bin/mmctl && printf "yes"),yes)
-	@echo mmctl installed
-else ifeq ($(PLATFORM),Darwin)
-	@echo Downloading prepackaged binary: https://github.com/mattermost/mmctl/releases/$(MMCTL_REL_TO_DOWNLOAD)
-	@MMCTL_FILE="darwin_amd64.tar" && curl -f -O -L https://github.com/mattermost/mmctl/releases/download/$(MMCTL_REL_TO_DOWNLOAD)/$$MMCTL_FILE && tar -xvf $$MMCTL_FILE -C bin && rm $$MMCTL_FILE
-else ifeq ($(PLATFORM),Linux)
-	@echo Downloading prepackaged binary: https://github.com/mattermost/mmctl/releases/$(MMCTL_REL_TO_DOWNLOAD)
-	@MMCTL_FILE="linux_amd64.tar" && curl -f -O -L https://github.com/mattermost/mmctl/releases/download/$(MMCTL_REL_TO_DOWNLOAD)/$$MMCTL_FILE && tar -xvf $$MMCTL_FILE -C bin && rm $$MMCTL_FILE
-else ifeq ($(PLATFORM),Windows)
-	@echo Downloading prepackaged binary: https://github.com/mattermost/mmctl/releases/$(MMCTL_REL_TO_DOWNLOAD)
-	@MMCTL_FILE="windows_amd64.zip" && curl -f -O -L https://github.com/mattermost/mmctl/releases/download/$(MMCTL_REL_TO_DOWNLOAD)/$$MMCTL_FILE && unzip -o $$MMCTL_FILE -d bin && rm $$MMCTL_FILE
+	@echo "mmctl already exists in bin/mmctl not downloading a new version."
 else
-	@echo "mmctl error: can't detect OS"
+	@MMCTL_VERSION=$$(scripts/get_latest_release.sh mattermost/mmctl release-); if [ $$? -eq 0 ]; then \
+		scripts/download_mmctl_release.sh $$MMCTL_VERSION; \
+	else \
+		echo $$MMCTL_VERSION; \
+		exit 1; \
+	fi;
 endif
 
 golangci-lint: ## Run golangci-lint on codebase