Add License Expiry Metric (#15483)

* add license expiry metric

* Update metrics test with default value to the new license metrics

* Add the changes of the black-lint command

* Update awx/main/analytics/metrics.py

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Co-authored-by: Seth Foster <fosterseth@users.noreply.github.com>

awx/main/tests/functional/analytics/test_metrics.py

@@ -30,6 +30,7 @@ EXPECTED_VALUES = {
     'awx_license_instance_free': 0,
     'awx_pending_jobs_total': 0,
     'awx_database_connections_total': 1,
+    'awx_license_expiry': 0,
 }