### Summary

I know there is some ongoing work to mitigate these problems, but since I'm not aware which parts have already been addressed and which not, I want to share some common failures here which I've seen during the last days:

1. When running `ansible-test sanity --color -v --junit --coverage-check --changed --docker --base-branch origin/main --skip-test pylint --skip-test ansible-doc --skip-test validate-modules --allow-disabled` in CI, the Python 2.6 `import` test fails:
```
02:05 ERROR: Command "/root/ansible_collections/community/general/tests/output/.tmp/sanity/import/minimal-py26/bin/python /root/ansible/test/lib/ansible_test/_data/quiet_pip.py install --disable-pip-version-check coverage -c /root/ansible/test/lib/ansible_test/_data/requirements/constraints.txt" returned exit status 1.
02:05 >>> Standard Error
02:05 Could not find a version that satisfies the requirement coverage<5.0.0,>=4.5.1 (from -c /root/ansible/test/lib/ansible_test/_data/requirements/constraints.txt (line 2)) (from versions: )
02:05 No matching distribution found for coverage<5.0.0,>=4.5.1 (from -c /root/ansible/test/lib/ansible_test/_data/requirements/constraints.txt (line 2))
02:05 >>> Standard Output
02:05 Collecting coverage<5.0.0,>=4.5.1 (from -c /root/ansible/test/lib/ansible_test/_data/requirements/constraints.txt (line 2))
```
(See https://app.shippable.com/github/ansible-collections/community.general/runs/8257/1/console for the full log)

2. When running unit tests for Python 2.6 with `ansible-test units -v --color --docker --coverage` with `unittest2 ; python_version < '2.7'` in tests/unit/requirements.txt, it fails:
```
Run command: /usr/bin/python2.6 /root/ansible/test/lib/ansible_test/_data/quiet_pip.py install --disable-pip-version-check -r /root/ansible/test/lib/ansible_test/_data/requirements/units.txt -r tests/unit/requirements.txt coverage -c /root/ansible/test/lib/ansible_test/_data/requirements/constraints.txt
Collecting unittest2 (from -r tests/unit/requirements.txt (line 1))
  Could not find a version that satisfies the requirement unittest2 (from -r tests/unit/requirements.txt (line 1)) (from versions: )
No matching distribution found for unittest2 (from -r tests/unit/requirements.txt (line 1))
ERROR: Command "/usr/bin/python2.6 /root/ansible/test/lib/ansible_test/_data/quiet_pip.py install --disable-pip-version-check -r /root/ansible/test/lib/ansible_test/_data/requirements/units.txt -r tests/unit/requirements.txt coverage -c /root/ansible/test/lib/ansible_test/_data/requirements/constraints.txt" returned exit status 1.
```
(See https://github.com/ansible-collections/community.hrobot/runs/2264772861?check_suite_focus=true)


### Issue Type

Bug Report

### Component Name

ansible-test

### Ansible Version

```console (paste below)
devel
```


### Configuration

...

### OS / Environment

...

### Steps to Reproduce

...

### Expected Results

...

### Actual Results

...
skipped = [target.name for target in targets if skip in target.aliases and target.name not in override]
        if skipped:
            exclude.extend(skipped)
            display.warning('Excluding tests marked "%s" which require --allow-unstable or prefixing with "unstable/": %s'
                            % (skip.rstrip('/'), ', '.join(skipped)))
    
    if isinstance(args, WindowsIntegrationConfig) and args.windows:
        all_skipped = []
        not_skipped = []
        for target in targets:
            if "skip/windows/" not in target.aliases:
                continue
            skip_valid = []
            skip_missing = []
            for version in args.windows:
                if "skip/windows/%s/" % version in target.aliases:
                    skip_valid.append(version)
                else:
                    skip_missing.append(version)
            if skip_missing and skip_valid:
                not_skipped.append((target.name, skip_valid, skip_missing))
            elif skip_valid:
                all_skipped.append(target.name)
        if all_skipped:
            exclude.extend(all_skipped)
            skip_aliases = ["skip/windows/%s/" % w for w in args.windows]
            display.warning('Excluding tests marked "%s" which are set to skip with --windows %s: %s'
                            % ('", "'.join(skip_aliases), ', '.join(args.windows), ', '.join(all_skipped)))
        if not_skipped:
            for target, skip_valid, skip_missing in not_skipped: