Fix false positive reports in is_handler function

[MalKeshar]

Found in the process of writing and checking custom rules.

The "is_handler" function considers all tasks from the file to be handlers if the file name contains the substring "handlers".

Therefore, all tasks in the check_handlers_playbook.yaml playbook were accepted as handlers.

I'm not sure if it's worth relying on the filename or path at all. But if we do, then maybe it makes sense to look for the full string, not just a part of it.

[MalKeshar]

Actually there is one more issue with detecting handlers. It is triggers in role handlers and not in plain playbook

This task will be detected as handler

- name: Reload sysctl (good handler)
  ansible.builtin.shell:
    cmd: "sysctl --system -p"
  changed_when: false

because it's object has attribute __file__

DEBUG    file_name: roles/xservice/handlers/main.yaml
DEBUG    self.position: .[3]
DEBUG    Running rule task-has-tag
DEBUG    Debug: task: Reload sysctl (good handler), args: {'cmd': 'sysctl --system -p'}, action: {'__ansible_module__': 'shell', '__ansible_module_original__': 'ansible.builtin.shell', 'cmd': 'sysctl --system -p', '__line__': 3, '__file__': PosixPath('roles/xservice/handlers/main.yaml')}

This task won't be detected as handler

- name: Reload sysctl ( bad handler)
  ansible.builtin.shell: "sysctl --system -p"
  changed_when: false

because it's object hasn't attribute __file__

DEBUG    file_name: roles/xservice/handlers/main.yaml
DEBUG    self.position: .[0]
DEBUG    Debug: task: Reload sysctl (bad handler), args: {'_raw_params': 'sysctl --system -p'}, action: {'__ansible_module__': 'shell', '__ansible_module_original__': 'ansible.builtin.shell', '_raw_params': 'sysctl --system -p'}

Both "self.position" don't have "handlers" word in it.

This function probably requires some redesign. Unfortunally python is not my lang, so I'm not gonna dig it dipper by myself.

env:

OS: ubuntu 22.04
Python: 3.10.12
ansible                   8.7.0
ansible-compat            24.5.1
ansible-core              2.15.11
ansible-lint              24.5.0