installer: T7034: fail the upgrade if image flavors do not match

[dmbaturin]

Change summary

Do not allow upgrades to non-matching flavors under any circumstances.

We already have LTS flavors where upgrading a platform-specific flavor to a generic ISO can break the system, and now that we have flavors for all platforms, there is no reason to upgrade anything to a flavor that isn't the same.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

Related PR(s)

How to test / Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[github-actions]

👍
No issues in PR Title / Commit Title

[github-actions]

CI integration 👍 passed!

Details

CI logs

• CLI Smoketests (no interfaces) 👍 passed
• CLI Smoketests (interfaces only) 👍 passed
• Config tests 👍 passed
• RAID1 tests 👍 passed
• TPM tests 👍 passed

[sever-sever]

There could be a use case when clients in AWS want to test some rolling features; this way, they cannot do it.
Some force option could be a compromise.

This action could make brick from your router. Are you sure you want to update? [N/y]: yes 
....