Use predefined go command consistently (#13216)

Makefile

@@ -165,32 +165,32 @@ ifeq ($(BUILD_ENTERPRISE_READY),true)
 endif
 
 i18n-extract: ## Extract strings for translation from the source code
-	env GO111MODULE=off go get -u github.com/mattermost/mattermost-utilities/mmgotool
+	env GO111MODULE=off $(GO) get -u github.com/mattermost/mattermost-utilities/mmgotool
 	$(GOPATH)/bin/mmgotool i18n extract
 
 store-mocks: ## Creates mock files.
-	env GO111MODULE=off go get -u github.com/vektra/mockery/...
+	env GO111MODULE=off $(GO) get -u github.com/vektra/mockery/...
 	$(GOPATH)/bin/mockery -dir store -all -output store/storetest/mocks -note 'Regenerate this file using `make store-mocks`.'
 
 store-layers: ## Generate layers for the store
 	$(GO) generate $(GOFLAGS) ./store
 
 filesstore-mocks: ## Creates mock files.
-	env GO111MODULE=off go get -u github.com/vektra/mockery/...
+	env GO111MODULE=off $(GO) get -u github.com/vektra/mockery/...
 	$(GOPATH)/bin/mockery -dir services/filesstore -all -output services/filesstore/mocks -note 'Regenerate this file using `make filesstore-mocks`.'
 
 ldap-mocks: ## Creates mock files for ldap.
-	env GO111MODULE=off go get -u github.com/vektra/mockery/...
+	env GO111MODULE=off $(GO) get -u github.com/vektra/mockery/...
 	$(GOPATH)/bin/mockery -dir enterprise/ldap -all -output enterprise/ldap/mocks -note 'Regenerate this file using `make ldap-mocks`.'
 
 plugin-mocks: ## Creates mock files for plugins.
-	env GO111MODULE=off go get -u github.com/vektra/mockery/...
+	env GO111MODULE=off $(GO) get -u github.com/vektra/mockery/...
 	$(GOPATH)/bin/mockery -dir plugin -name API -output plugin/plugintest -outpkg plugintest -case underscore -note 'Regenerate this file using `make plugin-mocks`.'
 	$(GOPATH)/bin/mockery -dir plugin -name Hooks -output plugin/plugintest -outpkg plugintest -case underscore -note 'Regenerate this file using `make plugin-mocks`.'
 	$(GOPATH)/bin/mockery -dir plugin -name Helpers -output plugin/plugintest -outpkg plugintest -case underscore -note 'Regenerate this file using `make plugin-mocks`.'
 
 einterfaces-mocks: ## Creates mock files for einterfaces.
-	env GO111MODULE=off go get -u github.com/vektra/mockery/...
+	env GO111MODULE=off $(GO) get -u github.com/vektra/mockery/...
 	$(GOPATH)/bin/mockery -dir einterfaces -all -output einterfaces/mocks -note 'Regenerate this file using `make einterfaces-mocks`.'
 
 pluginapi: ## Generates api and hooks glue code for plugins
@@ -244,7 +244,7 @@ do-cover-file: ## Creates the test coverage report file.
 	@echo "mode: count" > cover.out
 
 go-junit-report:
-	env GO111MODULE=off go get -u github.com/jstemmer/go-junit-report
+	env GO111MODULE=off $(GO) get -u github.com/jstemmer/go-junit-report
 
 test-compile: ## Compile tests.
 	@echo COMPILE TESTS
@@ -414,7 +414,7 @@ clean: stop-docker ## Clean up everything except persistant server data.
 	@echo Cleaning
 
 	rm -Rf $(DIST_ROOT)
-	go clean $(GOFLAGS) -i ./...
+	$(GO) clean $(GOFLAGS) -i ./...
 
 	cd $(BUILD_WEBAPP_DIR) && $(MAKE) clean
 
@@ -446,13 +446,13 @@ update-dependencies: ## Uses go get -u to update all the dependencies while hold
 	@echo Updating Dependencies
 
 	# Update all dependencies (does not update across major versions)
-	go get -u
+	$(GO) get -u
 
 	# Tidy up
-	go mod tidy
+	$(GO) mod tidy
 
 	# Copy everything to vendor directory
-	go mod vendor
+	$(GO) mod vendor
 
 
 todo: ## Display TODO and FIXME items in the source code.