Prevent support libraries from compiling into Gitea (#10964)

* Prevent support libraries from compiling into Gitea

* Fix tag position

* Fix golangci-lint errors

* Refactor to make it work

Co-authored-by: Guillermo Prandi <guillep2k@users.noreply.github.com>

Makefile

@@ -301,7 +301,7 @@ unit-test-coverage:
 
 .PHONY: vendor
 vendor:
-	$(GO) mod tidy && $(GO) mod vendor
+	$(GO) mod tidy && TAGS="$(TAGS) vendor" $(GO) mod vendor
 
 .PHONY: test-vendor
 test-vendor: vendor