MM-43341: Allow test to run (#24470)

When I fixed the flaky test in https://github.com/mattermost/mattermost/pull/20140,
I actually forgot to uncomment this line to allow the test to run.

Thanks to @hanzei for spotting this.

https://mattermost.atlassian.net/browse/MM-43341
```release-note
NONE
```

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/import_functions_test.go

@@ -722,7 +722,6 @@ func TestImportImportChannel(t *testing.T) {
 }
 
 func TestImportImportUser(t *testing.T) {
-	t.Skip("MM-43341")
 	th := Setup(t)
 	defer th.TearDown()