[Chronicle] Provide better REST API / UI error message in the case that the current chronicle leader is in the quorum failover nodes (was:Unsafe failover of nodes involving orch fails with error not in peers)

guides/gradlew --refresh-dependencies testrunner -P jython=/opt/jython/bin/jython -P 'args=-i /tmp/durability_volume.ini rerun=False,get-cbcollect-info=True -t bucket_collections.collections_quorum_loss.CollectionsQuorumLoss.test_quorum_loss_failover,nodes_init=5,bucket_spec=multi_bucket.buckets_all_membase_for_quorum_loss,replicas=3,num_node_failures=3,failover_orchestrator=True,quota_percent=80,GROUP=P2'

+----------------+----------+-----------------------+---------------+--------------+

| Nodes          | Services | Version               | CPU           | Status       |

+----------------+----------+-----------------------+---------------+--------------+

| 172.23.105.215 | kv       | 7.0.0-4721-enterprise | 3.56150543066 | Cluster node |

| 172.23.105.217 | None     |                       |               | <--- IN ---  |

| 172.23.105.219 | None     |                       |               | <--- IN ---  |

| 172.23.105.220 | None     |                       |               | <--- IN ---  |

| 172.23.106.237 | None     |                       |               | <--- IN ---  |

+----------------+----------+-----------------------+---------------+--------------+

2021-03-19 01:37:19,776 | test  | INFO    | MainThread | [collections_quorum_loss:test_quorum_loss_failover:272] Failing over nodes explicitly [ip:172.23.105.215 port:8091 ssh_username:root, ip:172.23.105.217 port:8091 ssh_username:root, ip:172.23.105.219 port:8091 ssh_username:root]

2021-03-19 01:37:20,200 | test  | ERROR   | pool-1-thread-17 | [rest_client:_http_request:748] POST http://172.23.106.237:8091/controller/failOver body: otpNode=ns_1%40172.23.105.215&otpNode=ns_1%40172.23.105.217&otpNode=ns_1%40172.23.105.219&allowUnsafe=true headers: {'Accept': '*/*', 'Connection': 'close', 'Authorization': 'Basic QWRtaW5pc3RyYXRvcjpwYXNzd29yZA==\n', 'Content-Type': 'application/x-www-form-urlencoded'} error: 500 reason: status: 500, content: Unexpected server error: {error,

                             {not_in_peers,'ns_1@172.23.105.215',

                                 ['ns_1@172.23.105.220',

                                  'ns_1@172.23.106.237']}} Unexpected server error: {error,

                             {not_in_peers,'ns_1@172.23.105.215',

                                 ['ns_1@172.23.105.220',

                                  'ns_1@172.23.106.237']}} auth: Administrator:password

[ns_server:error,2021-03-19T01:37:20.188-07:00,ns_1@172.23.105.215:<0.6898.0>:chronicle_master:handle_call:175]Unsuccesfull quorum loss failover. ({not_in_peers,'ns_1@172.23.105.215',

                                     ['ns_1@172.23.105.220',

                                      'ns_1@172.23.106.237']}).