[Ingest Manager] New Agent configuration doesn't start at Rev 1

[mostlyjason]

Kibana version:
8.0 snapshot

Describe the bug:
After creating a new Agent configuration it appears to start at rev 2.

Steps to reproduce:

1. Add a new Agent configuration in Ingest Manager
2. View the revision number after its created

Expected behavior:
It should start at revision 1.

Screenshots (if relevant):
I just created the top 3 configurations and they all start at rev 2.

[elasticmachine]

Pinging @elastic/ingest-management (Team:Ingest Management)

[ph]

This isn't great UI but I don't find it critical, I believe its because we do two saves on the Agent configuration document?

[nchaulet]

Yes it because we create the configuration and add the datasource after that cause a bump of revision.