Remove unnecessary struct2interface dependency (#13929)

* Remove unnecessary struct2interface dependency

Running go mod tidy on the repo removes it.
This was also preventing 1.14beta from running the repo,
because now it verifies modules.txt with go.mod, which had a mismatch.

* fixing CI

* Fix test-server target

* Fix some discrepancies in vendor

* Removing the Makefile target for now

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

Makefile

@@ -293,6 +293,17 @@ test-db-migration: start-docker ## Gets diff of upgrade vs new instance schemas.
 	./scripts/mysql-migration-test.sh
 	./scripts/psql-migration-test.sh
 
+gomodtidy:
+	@cp go.mod go.mod.orig
+	@cp go.sum go.sum.orig
+	$(GO) mod tidy
+	@if [ "$$(diff go.mod go.mod.orig)" != "" -o "$$(diff go.sum go.sum.orig)" != "" ]; then \
+		echo "go.mod/go.sum was modified. \ndiff- $$(diff go.mod go.mod.orig) \n$$(diff go.sum go.sum.orig) \nRun \"go mod tidy\"."; \
+		rm go.*.orig; \
+		exit 1; \
+	fi;
+	@rm go.*.orig;
+
 test-server: start-docker go-junit-report do-cover-file ## Runs tests.
 ifeq ($(BUILD_ENTERPRISE_READY),true)
 	@echo Running all tests