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>

plugin/helpers_bots_test.go

@@ -572,7 +572,7 @@ func TestShouldProcessMessage(t *testing.T) {
 		api.On("KVGet", plugin.BotUserKey).Return(nil, nil)
 
 		shouldProcessMessage, err := p.ShouldProcessMessage(&model.Post{ChannelId: channelID, UserId: userID}, plugin.BotID(expectedBotID))
-		assert.Nil(t, err)
+		assert.NoError(t, err)
 
 		assert.True(t, shouldProcessMessage)
 	})