Undercloud: Deprecate unused scheduler_max_attempts

The option was used to tune behavior of nova-scheduler but has had no
effect since nova was removed from undercloud.

Change-Id: Ie01f4663b944a12c8ef11addf95b6b3574cb5ee7

releasenotes/notes/deprecate-uc-scheduler_max_attempts-9018c4635507940b.yaml

@@ -0,0 +1,6 @@
+---
+deprecations:
+  - |
+    The ``[DEFAULT] scheduler_max_attempts`` option of undercloud.conf has been
+    deprecated. The option has had no effect since nova was removed from
+    undercloud.

tripleoclient/config/undercloud.py

@@ -287,6 +287,10 @@ class UndercloudConfig(StandaloneConfig):
                         ),
             cfg.IntOpt('scheduler_max_attempts',
                        default=30, min=1,
+                       deprecated_for_removal=True,
+                       deprecated_reason=_(
+                            'This option has no effect since nova was removed '
+                            'from undercloud.'),
                        help=_(
                            'Maximum number of attempts the scheduler will '
                            'make when deploying the instance. You should keep '

tripleoclient/v1/undercloud_config.py

@@ -64,7 +64,6 @@ PARAMETER_MAPPING = {
     'undercloud_debug': 'Debug',
     'certificate_generation_ca': 'CertmongerCA',
     'undercloud_public_host': 'CloudName',
-    'scheduler_max_attempts': 'NovaSchedulerMaxAttempts',
     'local_mtu': 'UndercloudLocalMtu',
     'clean_nodes': 'IronicAutomatedClean',
     'container_healthcheck_disabled': 'ContainerHealthcheckDisabled',