Enable the errorAssertions govet check for mattermost-server code (#17346)

* Enable the errorAssertions govet check for mattermost-server code

* Removing unnecesary change

* Fixing some tests

* Fixing tests

* Fixing more after merge

* Fixing new offending entries

* Fixing small vet checks

* Fixing new cases detected by govet

* Fixing remote_cluster_test errors

* Fixing assertion

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

services/remotecluster/ping_test.go

@@ -119,7 +119,7 @@ func TestPing(t *testing.T) {
 
 		wg.Wait()
 
-		assert.Nil(t, merr.ErrorOrNil())
+		assert.NoError(t, merr.ErrorOrNil())
 
 		assert.Equal(t, int32(NumRemotes), atomic.LoadInt32(&countWebReq))
 		t.Log(fmt.Sprintf("%d web requests counted;  %d expected",