Add ansible_distribution_major_version to macOS (#31708)

(cherry picked from commit 4dce9dc796)

lib/ansible/module_utils/facts/system/distribution.py

@@ -491,6 +491,8 @@ class Distribution(object):
         darwin_facts['distribution'] = 'MacOSX'
         rc, out, err = self.module.run_command("/usr/bin/sw_vers -productVersion")
         data = out.split()[-1]
+        if data:
+            darwin_facts['distribution_major_version'] = data.split('.')[0]
             darwin_facts['distribution_version'] = data
         return darwin_facts