fix: remove resolvedOfferings, defaults, and scheduling for containers not defined in app

[g-linville]

We discovered this bug earlier today while working on something else. If you do acorn update --image <image> <app name>, and containers that were previously defined in the app no longer are, the resolved offerings, defaults, and scheduling information would still be present in the app's status for the old containers, even though they are not in the app anymore. This PR adds logic to delete containers from these maps when they no longer exist in the app. I also added new unit tests that check for this.

Checklist

• [x] The title of this PR would make a good line in Acorn's Release Note's Changelog
• [ ] The title of this PR ends with a link to the main issue being address in parentheses, like: This is a title (#1216). Here's an example
• [x] All relevant issues are referenced in the PR description. NOTE: don't use GitHub keywords that auto-close issues
• [x] Commits follow contributing guidance
• [x] Automated tests added to cover the changes. If tests couldn't be added, an explanation is provided in the Verification and Testing section
• [x] Changes to user-facing functionality, API, CLI, and upgrade impacts are clearly called out in PR description
• [ ] PR has at least two approvals before merging (or a reasonable exception, like it's just a docs change)

[sangee2004]

Tested with - v0.10.1-rc1-21-g3964bbc9+3964bbc9

1. Deploy app with image that was built from Acornfile that has 2 containers ( con1 and con2)
2. Update app with an image that was built from Acornfile that has only 1 container (con1) After update , When examining app with acorn app -o json , resolvedOfferings and defaults have info for only con1 (there is no info about con2

When examining appinstance with akubectl get appinstances -o json , resolvedOfferings , defaults and scheduling have info for only con1 (there is no info about con2