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>

.gitignore

@@ -103,3 +103,4 @@ debug
 client
 __debug_bin
 report.xml
+go.*.orig