Skip self._parent on dynamic, defer grandparent for attr lookup

[sivel]

SUMMARY

Skip self._parent on dynamic, defer grandparent for attr lookup.

This solves the problem where we should look up the tree for attrs on static objects, when constructing attrs for tasks within dynamic.

Examples:

Block:

# delegate_to: localhost should be applied to tasks within the include as the attr is not applied to the include itself
- delegate_to: localhost
  block:
    - include_tasks: include_me.yml

import->include:

- import_tasks: import_me.yml
  delegate_to: localhost

# delegate_to: localhost should apply to tasks within include_tasks
- include_tasks: include_me.yml

This PR also backs out the _inheritable changes from 8e6ebae8bda

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

lib/ansible/playbook/block.py
lib/ansible/playbook/task.py

ANSIBLE VERSION

devel

ADDITIONAL INFORMATION

[sivel]

Test cases:

• 2.5: bug with include_tasks inside of import_tasks #38037
• Escalating roles with include_role, bug with block #36194

[sivel]

I ran the new tests against devel, and received:

TASK [assert] ******************************************************************
fatal: [testhost]: FAILED! => {
    "assertion": "block_include_result is skipped",
    "changed": false,
    "evaluated_to": false
}

fatal: [testhost]: FAILED! => {
    "assertion": "import_include_include_result is skipped",
    "changed": false,
    "evaluated_to": false
}

[sivel]

From the reproducer in #36194 I get expected results with this change:

TASK [whoami : shell] ************************************************************************************************************************************************************************************************************************
changed: [localhost] => {..., "stdout": "matt", "stdout_lines": ["matt"]}

TASK [include_role] **************************************************************************************************************************************************************************************************************************

TASK [whoami : shell] ************************************************************************************************************************************************************************************************************************
changed: [localhost] => {..., "stdout": "matt", "stdout_lines": ["matt"]}

TASK [include_role] **************************************************************************************************************************************************************************************************************************

TASK [whoami : shell] ************************************************************************************************************************************************************************************************************************
changed: [localhost] => {..., "stdout": "root", "stdout_lines": ["root"]}