<!--- Verify first that your issue is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Explain the problem briefly below -->

If you use the free strategy with a complex playbook that has a mix of regular tasks, roles and handlers, some nodes may fail because the strategy attempts to load ansible roles as files when handlers are run.

I tracked it down to the _do_handler_run in the lib/ansible/plugins/strategy/__init__.py because included_files are not check to see if they are a role before being included. 

https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/strategy/free.py#L240-L259
vs
https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/strategy/__init__.py#L1005-L1031

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
free.py

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.7
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/centos/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.6/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.6.8 (default, Nov 21 2019, 19:31:34) [GCC 8.3.1 20190507 (Red Hat 8.3.1-4)]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
CentOS8

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
TBD.
```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->

No error because it correctly loads the role

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below
fatal: [overcloud-novacompute-0]: FAILED! => {
    "reason": "Could not find or access '/home/centos/config-download/overcloud/tripleo_timezone' on the Ansible Controller. Traceback (most recent call last):\n  File \"/usr/lib/python3.6/site-packages/ansible/plugins/strategy/__init__.py\", line 869, in _load_included_file\n    data = self._loader.load_from_file(included_file._filename)\n  File \"/usr/lib/python3.6/site-packages/ansible/parsing/dataloader.py\", line 94, in load_from_file\n    (b_file_data, show_content) = self._get_file_contents(file_name)\n  File \"/usr/lib/python3.6/site-packages/ansible/parsing/dataloader.py\", line 162, in _get_file_contents\n    raise AnsibleFileNotFound(\"Unable to retrieve file contents\", file_name=file_name)\nansible.errors.AnsibleFileNotFound: Unable to retrieve file contents\nCould not find or access '/home/centos/config-download/overcloud/tripleo_timezone' on the Ansible Controller.\nIf you are using a module and expect the file to exist on the remote, see the remote_src option\n"
}

```

for handler_block in reversed(handler_blocks):
                for handler_task in handler_block.block:
                    if handler_task.name:
                        if not handler_task.cached_name:
                            if handler_templar.is_template(handler_task.name):
                                handler_templar.available_variables = self._variable_manager.get_vars(play=iterator._play,
                                                                                                      task=handler_task,
                                                                                                      _hosts=self._hosts_cache,
                                                                                                      _hosts_all=self._hosts_cache_all)
                                handler_task.name = handler_templar.template(handler_task.name)
                            handler_task.cached_name = True
                        try:
                            
                            
                            
                            
                            candidates = (
                                handler_task.name,
                                handler_task.get_name(include_role_fqcn=False),
                                handler_task.get_name(include_role_fqcn=True),
                            )
                            if handler_name in candidates:
                                return handler_task
                        except (UndefinedError, AnsibleUndefinedVariable):