MM-33913: Fix read-after-write issues with team member (#17173)

During LDAP sync, we would call AddTeamMember which had a read-after-write issue
where we would create a team member but then immediately after that
query the team member.

The same pattern was found in:
AddTeamMember
AddTeamMembers
AddTeamMemberByToken

To fix this, we just return the inserted team member from AddUserToTeam and use that
instead of query GetTeamMember again.

```release-note
NONE
```

https://mattermost.atlassian.net/browse/MM-33913

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

api4/user_test.go

@@ -378,7 +378,7 @@ func TestCreateUserWebSocketEvent(t *testing.T) {
 		guest, err := th.App.CreateGuest(guest)
 		require.Nil(t, err)
 
-		_, err = th.App.AddUserToTeam(th.BasicTeam.Id, guest.Id, "")
+		_, _, err = th.App.AddUserToTeam(th.BasicTeam.Id, guest.Id, "")
 		require.Nil(t, err)
 
 		_, err = th.App.AddUserToChannel(guest, th.BasicChannel)