fix(entrypoint): compare enabled app names to report disabled apps after upgrade

[joshtrichards]

Summary

Refactor disabled-app reporting in docker-entrypoint.sh into a helper and compare normalized enabled app names before and after occ upgrade.

Instead of diffing full occ app:list output and parsing human-readable diff output, this change extracts only enabled app names and compares those sets directly.

Why

The previous implementation had two problems:

1. False positives during upgrades

   • Apps that were upgraded but still enabled could be reported as disabled because the line in occ app:list changed (for example due to a version bump), and the script treated that as a removal.
   • e.g. [Bug]: Upgrade 31.0.10 > 32.0.1 apps go missing server#56093 (comment)

2. Alpine / BusyBox incompatibility

   • The code depended on parsing diff output using grep '<', which does not work reliably with BusyBox diff output on Alpine.

By comparing only enabled app names, the script now reports actual before-vs-after enablement changes instead of line-level text differences.

What changed

• Extract disabled-app reporting into a dedicated helper
• Normalize occ app:list output down to enabled app names only
• Compare the before/after app-name lists with comm
• Keep the upgrade flow behavior the same otherwise

Behavior before

• calendar 4.2.2 -> 4.2.3 could be reported as "disabled"
• Alpine images could produce an empty disabled-app list due to diff output format differences

Behavior after

• Upgraded-but-still-enabled apps are no longer reported as disabled
• Disabled-app reporting works without depending on diff output format

Notes

This is both a cleanup and a bug fix:

• the comparison logic is now easier to reason about
• the result matches the actual intent: report apps enabled before upgrade but
  not enabled after upgrade

Fixes #1911

Alternative to PR #2267