fix(gentoo): use `retry_options` to avoid spurious service failures

Use the `retry_options` on Gentoo, similar to how its already being used
across the state files for FreeBSD, since we're getting failures such as
this one:

* https://gitlab.com/myii/salt-formula/-/jobs/2285180374

salt/api.sls

   service.{{ salt_settings.api_service_details.state }}:
     - enable: {{ salt_settings.api_service_details.enabled }}
     - name: {{ salt_settings.api_service }}
-    {%- if grains.os_family == 'FreeBSD' %}
+    {%- if grains.os_family in ['FreeBSD', 'Gentoo'] %}
     - retry: {{ salt_settings.retry_options | json }}
     {%- endif %}
     - require:

salt/master.sls

   service.{{ salt_settings.master_service_details.state }}:
     - enable: {{ salt_settings.master_service_details.enabled }}
     - name: {{ salt_settings.master_service }}
-    {%- if grains.os_family == 'FreeBSD' %}
+    {%- if grains.os_family in ['FreeBSD', 'Gentoo'] %}
     - retry: {{ salt_settings.retry_options | json }}
     {%- endif %}
     - watch:

salt/minion.sls

   service.{{ salt_settings.minion_service_details.state }}:
     - enable: {{ salt_settings.minion_service_details.enabled }}
     - name: {{ salt_settings.minion_service }}
-    {%- if grains.os_family == 'FreeBSD' %}
+    {%- if grains.os_family in ['FreeBSD', 'Gentoo'] %}
     - retry: {{ salt_settings.retry_options | json }}
     {%- endif %}
     - watch:

salt/standalone.sls

     - enable: False
   {%- endif %}
     - name: {{ salt_settings.minion_service }}
-    {%- if grains.os_family == 'FreeBSD' %}
+    {%- if grains.os_family in ['FreeBSD', 'Gentoo'] %}
     - retry: {{ salt_settings.retry_options | json }}
     {%- endif %}
     - require:

salt/syndic.sls

   service.running:
     - enable: True
     - name: {{ salt_settings.syndic_service }}
-    {%- if grains.os_family == 'FreeBSD' %}
+    {%- if grains.os_family in ['FreeBSD', 'Gentoo'] %}
     - retry: {{ salt_settings.retry_options | json }}
     {%- endif %}
     - require: