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>

app/slashcommands/command_invite_test.go

@@ -41,7 +41,7 @@ func TestInviteProvider(t *testing.T) {
 		Description: "a test bot",
 	})
 	require.Nil(t, err)
-	_, err = th.App.AddUserToTeam(th.BasicTeam.Id, bot2.UserId, basicUser3.Id)
+	_, _, err = th.App.AddUserToTeam(th.BasicTeam.Id, bot2.UserId, basicUser3.Id)
 	require.Nil(t, err)
 
 	bot3, err := th.App.CreateBot(&model.Bot{
@@ -50,7 +50,7 @@ func TestInviteProvider(t *testing.T) {
 		Description: "a test bot",
 	})
 	require.Nil(t, err)
-	_, err = th.App.AddUserToTeam(th.BasicTeam.Id, bot3.UserId, basicUser3.Id)
+	_, _, err = th.App.AddUserToTeam(th.BasicTeam.Id, bot3.UserId, basicUser3.Id)
 	require.Nil(t, err)
 	err = th.App.RemoveUserFromTeam(th.BasicTeam.Id, bot3.UserId, basicUser3.Id)
 	require.Nil(t, err)