fix: automatic progressive releases

[Lukewh]

Done

If a progressive release has been marked as "automatic" an explicit release is not created, therefore we need to:

1. Check the current release against the channel map (like we do to get the up-to-date percentage of current users.
2. Update the percentage of the release if the channel map has a different percentage
3. if the progressive release has "finished" the percentage in the channel map will be null, in this case set the percentage to 100.

How to QA

• Visit https://snapcraft-io-5219.demos.haus/firefox/releases
• The stable track should show progressive releases, if you open the history the target should be shown as 100
• Visit https://snapcraft-io-5219.demos.haus/deno/releases
• The beta track should show progressive releases, it should be set to 41% correctly.

Testing

• This PR has tests - covered by current tests
• No testing required (explain why):

Issue / Card

Fixes https://warthogs.atlassian.net/browse/WD-23858

Screenshots

[webteam-app]

Demo

Jenkins

demos.haus

[ilayda-cp]

🚀