Clarify OAuth cloud v enterprise config instructions

[lwandz13]

This was posted in the docs team Slack channel regarding clarifying a difference between Cloud config v Enterprise:

https://raintank-corp.slack.com/archives/C5PG2JK8W/p1713983909694019

So I had someone trying to configure oauth with the docs here:
https://grafana.com/docs/grafana/latest/setup-grafana/configure-security/c:onfigure-authentication/google/#configure-team-sync-for-google-oauth
And it wasn't clear that if you are using grafana cloud, it's not configured in a config file, it's configured in the screenshot
image.png

https://grafana.com/docs/grafana/latest/setup-grafana/configure-security/configure-authentication/google/#configure-team-sync-for-google-oauth