### 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

...
exclude,  
                  require,  
                  integration_targets,  
                  ):  
    """Delegate ansible-test execution to a virtual environment using venv or virtualenv."""
    if args.python:
        versions = (args.python_version,)
    else:
        versions = SUPPORTED_PYTHON_VERSIONS
    if args.httptester:
        needs_httptester = sorted(target.name for target in integration_targets if 'needs/httptester/' in target.aliases)
        if needs_httptester:
            display.warning('Use --docker or --remote to enable httptester for tests marked "needs/httptester": %s' % ', '.join(needs_httptester))
    if args.venv_system_site_packages:
        suffix = '-ssp'
    else:
        suffix = ''
    venvs = dict((version, os.path.join(ResultType.TMP.path, 'delegation', 'python%s%s' % (version, suffix))) for version in versions)
    venvs = dict((version, path) for version, path in venvs.items() if create_virtual_environment(args, version, path, args.venv_system_site_packages))
    if not venvs:
        raise ApplicationError('No usable virtual environment support found.')
    options = {
        '--venv': 0,
        '--venv-system-site-packages': 0,
    }
    with tempdir() as inject_path:
        for version, path in venvs.items():
            create_interpreter_wrapper(os.path.join(path, 'bin', 'python'), os.path.join(inject_path, 'python%s' % version))
        python_interpreter = os.path.join(inject_path, 'python%s' % args.python_version)
        cmd = generate_command(args, python_interpreter, ANSIBLE_BIN_PATH, data_context().content.root, options, exclude, require)