More containers are restarted when combine with with_dict and notify

[Xing Zhang]

**Bug Report**

What happened:
When a container changed, such as we changes configurations in nova-api,
this will restart all nova containers, which is not the expected result
especially in production environment.
See logs at [1] pasted below.

What you expected to happen:
Only restart the one needs to be restarted

How to reproduce it (minimal and precise):
1. create or modify config file in "{{ node_custom_config }}/nova/nova-api.conf"
2. add or change some config
[DEFAULT]
reserved_host_memory_mb = 64
3. deploy/reconfigure/upgrade using kolla-ansible

**Environment**:
config tasks using with_dict and notify after https://review.opendev.org/#/c/647699/
e.g.
some tasks in tasks/config.yml
- name: Copying over extra CA certificates
  become: true
  copy:
    src: "{{ node_config }}/certificates/ca/"
    dest: "{{ node_config_directory }}/{{ item.key }}/ca-certificates"
    mode: "0644"
  when:
    - item.value.enabled | bool
    - inventory_hostname in groups[item.value.group]
    - kolla_copy_ca_into_containers | bool
  with_dict: "{{ nova_services }}"
  notify:
    - "Restart {{ item.key }} container"

- name: Copying over nova.conf
  become: true
  vars:
    service_name: "{{ item.key }}"
  merge_configs:
    sources:
      - "{{ role_path }}/templates/nova.conf.j2"
      - "{{ node_custom_config }}/global.conf"
      - "{{ node_custom_config }}/nova.conf"
      - "{{ node_custom_config }}/nova/{{ item.key }}.conf"
      - "{{ node_custom_config }}/nova/{{ inventory_hostname }}/nova.conf"
    dest: "{{ node_config_directory }}/{{ item.key }}/nova.conf"
    mode: "0660"
  when:
    - inventory_hostname in groups[item.value.group]
    - item.value.enabled | bool
    - item.key in nova_services_require_nova_conf
  with_dict: "{{ nova_services }}"
  notify:
    - "Restart {{ item.key }} container"

[1] ansible logs
TASK [nova : Copying over nova.conf] *****
skipping: [control1] ...
skipping: [control2] ...
...
ok: [control3] ...
...
changed: [control1] ...
...
RUNNING HANDLER [nova : Restart placement-api container] *****
changed: [control1]

RUNNING HANDLER [nova : Restart nova-api container] *****
changed: [control1]

RUNNING HANDLER [nova : Restart nova-scheduler container] *****
changed: [control1]

RUNNING HANDLER [nova : Restart nova-conductor container] *****
changed: [control1]

RUNNING HANDLER [nova : Restart nova-consoleauth container] *****
changed: [control1]

RUNNING HANDLER [nova : Restart nova-novncproxy container] *****
changed: [control1]

[Xing Zhang (xingzhang)]

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