Disabling Maintenance mode does not trigger an event

Overview of the Issue

I was looking at disabling alerts in consul-alerts when host is in maintenance mode: https://github.com/AcalephStorage/consul-alerts/issues/213

And I found out that while consul-alerts does create an entry in the KV store for _node_maintenance service check when maintenance mode is disabled, it does NOT update that entry once maintenance mode is disabled:

So I tried running consul watch myself same as the consul-alerts service does and I found out that disabling maintenance mode does not trigger an event:

 > consul watch -type checks cat | jq '.[] | select(.CheckID == "_node_maintenance")'
{
  "Node": "node-01.example.org",
  "CheckID": "_node_maintenance",
  "Name": "Node Maintenance Mode",
  "Status": "critical",
  "Notes": "TEST",
  "Output": "",
  "ServiceID": "",
  "ServiceName": "",
  "ServiceTags": [],
  "Type": "maintenance",
  "Definition": {
    "Interval": "0s",
    "Timeout": "0s",
    "DeregisterCriticalServiceAfter": "0s",
    "HTTP": "",
    "Header": null,
    "Method": "",
    "Body": "",
    "TLSServerName": "",
    "TLSSkipVerify": false,
    "TCP": ""
  },
  "CreateIndex": 67303625,
  "ModifyIndex": 67303625
}

I receive one event with Status set to critical, but no recovery to passing, since the _node_maintenance check is removed.

For this reason consul-alerts never updates its stage of _node_maintenance check.

Reproduction Steps

1. Use version 1.10.1
2. Run consul watch -type checks cat
3. See that no even is triggered for disabling of maintenance mode

Operating system and Environment details

Ubuntu 20.04.3, x86_64