Move HostVars instantiation to VariableManager

Change:
- TQM was only using this for its side effect. Let VariableManager do
  the work instead.

Test Plan:
- CI

Signed-off-by: Rick Elrod <rick@elrod.me>

changelogs/fragments/hostvars-to-varsmanager.yml

@@ -0,0 +1,3 @@
+minor_changes:
+  - hostvars - ``HostVars`` is now instantiated in ``VariableManager`` instead of in ``TaskQueueManager``
+  - hostvars - removed unused ``HostVars#set_variable_manager``

lib/ansible/executor/task_queue_manager.py

@@ -38,7 +38,6 @@ from ansible.playbook.task import Task
 from ansible.plugins.loader import callback_loader, strategy_loader, module_loader
 from ansible.plugins.callback import CallbackBase
 from ansible.template import Templar
-from ansible.vars.hostvars import HostVars
 from ansible.vars.reserved import warn_if_reserved
 from ansible.utils.display import Display
 from ansible.utils.lock import lock_decorator
@@ -237,12 +236,6 @@ class TaskQueueManager:
         new_play.post_validate(templar)
         new_play.handlers = new_play.compile_roles_handlers() + new_play.handlers
 
-        self.hostvars = HostVars(
-            inventory=self._inventory,
-            variable_manager=self._variable_manager,
-            loader=self._loader,
-        )
-
         play_context = PlayContext(new_play, self.passwords, self._connection_lockfile.fileno())
         if (self._stdout_callback and
                 hasattr(self._stdout_callback, 'set_play_context')):

lib/ansible/vars/hostvars.py

@@ -50,13 +50,8 @@ class HostVars(Mapping):
 
     def __init__(self, inventory, variable_manager, loader):
         self._inventory = inventory
-        self._loader = loader
-        self._variable_manager = variable_manager
-        variable_manager._hostvars = self
-
-    def set_variable_manager(self, variable_manager):
         self._variable_manager = variable_manager
-        variable_manager._hostvars = self
+        self._loader = loader
 
     def set_inventory(self, inventory):
         self._inventory = inventory

lib/ansible/vars/manager.py

@@ -46,6 +46,7 @@ from ansible.utils.listify import listify_lookup_plugin_terms
 from ansible.utils.vars import combine_vars, load_extra_vars, load_options_vars
 from ansible.utils.unsafe_proxy import wrap_var
 from ansible.vars.clean import namespace_facts, clean_facts
+from ansible.vars.hostvars import HostVars
 from ansible.vars.plugins import get_vars_from_inventory_sources, get_vars_from_path
 
 display = Display()
@@ -85,8 +86,11 @@ class VariableManager:
         self._group_vars_files = defaultdict(dict)
         self._inventory = inventory
         self._loader = loader
-        self._hostvars = None
         self._omit_token = '__omit_place_holder__%s' % sha1(os.urandom(64)).hexdigest()
+        self._hostvars = HostVars(
+            inventory=self._inventory,
+            variable_manager=self,
+            loader=self._loader)
 
         self._options_vars = load_options_vars(version_info)