Avoid false positive import_playbook errors

Fixes: #4024

examples/.test_collection/.ansible-lint

@@ -0,0 +1 @@
+{}

examples/.test_collection/playbooks/bar.yml

@@ -0,0 +1,6 @@
+- name: Sample playbook
+  hosts: localhost
+  tasks:
+    - name: Sample task
+      ansible.builtin.debug:
+        msg: "Hello world!"

examples/.test_collection/playbooks/foo.yml

@@ -0,0 +1,2 @@
+- name: Fixture for bug 4024
+  import_playbook: examples.test_collection.bar.yml

src/ansiblelint/runner.py

@@ -519,7 +519,10 @@ def find_children(self, lintable: Lintable) -> list[Lintable]:
                     child.path = Path(path)
                     child.name = child.path.name
 
-                results.append(child)
+                # If filename looks like a FQCN, we do not add it because we
+                # cannot load it directly. namespace.collection_name.filename.yml
+                if child.filename.count(".") != 3 or child.path.exists():
+                    results.append(child)
         return results
 
     def play_children(