MM-29107: Fix race in LDAP login (#16239)

* MM-29107: Fix race in LDAP login

We remove the goroutine to make things synchronous.

This removes the race and makes things more reliable.
It is already tested by TestLogin in ldap_test.go in -race mode.

https://mattermost.atlassian.net/browse/MM-29107

```release-note
NONE
```

* Address review comments

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

einterfaces/mocks/LdapInterface.go

@@ -305,6 +305,6 @@ func (_m *LdapInterface) SwitchToLdap(userId string, ldapId string, ldapPassword
 }
 
 // UpdateProfilePictureIfNecessary provides a mock function with given fields: _a0, _a1
-func (_m *LdapInterface) UpdateProfilePictureIfNecessary(_a0 model.User, _a1 *model.Session) {
+func (_m *LdapInterface) UpdateProfilePictureIfNecessary(_a0 model.User, _a1 model.Session) {
 	_m.Called(_a0, _a1)
 }