Remove make website-test (#3706)

Remove `make website-test` because of the latest community commit:
`Remove make website-test and friends`
hashicorp/terraform-website@6d41be4

Author: zhangtbj

GNUmakefile

@@ -50,13 +50,6 @@ ifeq (,$(wildcard $(GOPATH)/src/$(WEBSITE_REPO)))
 endif
 	@$(MAKE) -C $(GOPATH)/src/$(WEBSITE_REPO) website-provider PROVIDER_PATH=$(shell pwd) PROVIDER_NAME=$(PKG_NAME)
 
-website-test:
-ifeq (,$(wildcard $(GOPATH)/src/$(WEBSITE_REPO)))
-	echo "$(WEBSITE_REPO) not found in your GOPATH (necessary for layouts and assets), get-ting..."
-	git clone https://$(WEBSITE_REPO) $(GOPATH)/src/$(WEBSITE_REPO)
-endif
-	@$(MAKE) -C $(GOPATH)/src/$(WEBSITE_REPO) website-provider-test PROVIDER_PATH=$(shell pwd) PROVIDER_NAME=$(PKG_NAME)
-
 docscheck:
 	@sh -c "'$(CURDIR)/scripts/docscheck.sh'"