fix subuid/subgid checks

"find" module only checks that files exist in a directory.
In this case it did not fail since the path was a file but there was
a warning:

  TASK [ikke_t.podman_container_systemd : check if user is in subuid file] ***********************
  [WARNING]: Skipped '/etc/subuid' path due to this access issue: '/etc/subuid' is not a directory
  ok: [hostname]

tasks/check_subid.yml

@@ -1,16 +1,12 @@
 ---
 
 - name: check if user is in subuid file
-  find:
-    path: /etc/subuid
-    contains: '^{{ container_run_as_user }}:.*$'
+  shell: "grep -i '^{{ container_run_as_user}}:.*' /etc/subuid"
   register: uid_line_found
   when: container_run_as_user != 'root'
 
 - name: check if group is in subgid file
-  find:
-    path: /etc/subgid
-    contains: '^{{ container_run_as_group }}:.*$'
+  shell: "grep -i '^{{ container_run_as_group }}:.*' /etc/subgid"
   register: gid_line_found
   when: container_run_as_group != 'root'
 
@@ -23,7 +19,7 @@
     mode: '0644'
     owner: root
     group: root
-  when: (not skip_subgid_change) and container_run_as_user != 'root' and not uid_line_found.matched
+  when: (not skip_subgid_change) and container_run_as_user != 'root' not uid_line_found.rc
 
 - name: ensure group is in subgid file, if it was missing
   lineinfile:
@@ -34,4 +30,4 @@
     mode: '0644'
     owner: root
     group: root
-  when: (not skip_subgid_change) and container_run_as_group != 'root' and not gid_line_found.matched
+  when: (not skip_subgid_change) and container_run_as_group != 'root' and gid_line_found.rc