Known limitation: Charm unsupported by test environment

## Description

Some charms declare `assumes: [unsupported-openstack]` (or similar `unsupported-*` tags, e.g.
`unsupported-obsolete`) in their CharmHub metadata. Our test environment cannot offer these
features, so any charm/track requiring one fails immediately at charm-resolution time, before
bundle building or deployment begins:

```
Charm '' does not satisfy assumes constraints; unmet requirement(s) ['feature=unsupported-openstack']
```

This isn't a solver bug or missing endpoint — the charm genuinely can't be tested here.

## Why won't-fix

Supporting these charms requires broader test-infrastructure work tracked separately (SQT-1081).
Nothing to fix in this repo today.

## Purpose

This issue is an attachment target: test executions failing with this `unsupported-*` assumes
signature should be attached here instead of triaged individually, since each is an instance of
the same known gap, not a new bug.

Use this issue as the attachment target for test executions that fail during charm resolution with an unsupported-* assumes requirement. Read the failure message and SQT-1081 for the broader infrastructure context; there is no code change to make in this repository, and done means attaching matching failures here rather than triaging them as separate bugs.

Written by the indexing model from the issue text.