[7.11][Telemetry] Add run and alert count to task state.

[pjhampton]

Summary

Previous work item: #84422
We are having difficulties testing this functionality in the BC. By adding a couple of month state items we hope to get to the bottom of this.

{
  "_index" : ".kibana-task-manager_1",
  "_type" : "_doc",
  "_id" : "task:security:endpoint-diagnostics:1.0.2",
  "_score" : 1.0,
  "_source" : {
    "migrationVersion" : {
      "task" : "7.6.0"
    },
    "task" : {
      "schedule" : {
        "interval" : "5m"
      },
      "taskType" : "security:endpoint-diagnostics",
      "retryAt" : null,
      "runAt" : "2020-12-22T14:18:41.976Z",
      "scope" : [
        "securitySolution"
      ],
      "startedAt" : null,
      "state" : """{"lastExecutionTimestamp":"2020-12-22T14:13:42.208Z","lastDiagAlertCount":0,"runs":9}""",
      "params" : """{"version":"1.0.2"}""",
      "ownerId" : null,
      "scheduledAt" : "2020-12-22T13:33:22.772Z",
      "attempts" : 0,
      "status" : "idle"
    },
    "references" : [ ],
    "updated_at" : "2020-12-22T14:13:42.506Z",
    "type" : "task"
  }
},

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 5bcf967

Metrics [docs]

✅ unchanged

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