[8.7] [Fleet] Disable FQDN selector by default (#152592) (#152687)

# Backport

This will backport the following commits from `main` to `8.7`:
- [[Fleet] Disable FQDN selector by default
(#152592)](#152592)

<!--- Backport version: 8.9.7 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Mark
Hopkin","email":"[email protected]"},"sourceCommit":{"committedDate":"2023-03-02T17:28:11Z","message":"[Fleet]
Disable FQDN selector by default (#152592)\n\n## Summary\r\n\r\nHide the
FQDN selector unless experimental feature is enabled. This\r\nselector
was added as part
of\r\nhttps://github.com//issues/149059\r\n\r\n###
Before:\r\n<img width=\"1073\" alt=\"Screenshot 2023-03-02 at 16 15
39\"\r\nsrc=\"https://user-images.githubusercontent.com/3315046/222487164-75024608-b0f1-419d-bbb0-299bad55cae1.png\">\r\n\r\n###
After:\r\n<img width=\"1112\" alt=\"Screenshot 2023-03-02 at 16 14
52\"\r\nsrc=\"https://user-images.githubusercontent.com/3315046/222487206-c58f76eb-6977-4d3a-908d-3b72b0f901fa.png\">\r\n\r\nCo-authored-by:
Kibana Machine
<[email protected]>","sha":"de482cbc9ebce0f6d424e90b3e98cffd9979e707","branchLabelMapping":{"^v8.8.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","Team:Fleet","v8.7.0","v8.8.0"],"number":152592,"url":"https://github.com/elastic/kibana/pull/152592","mergeCommit":{"message":"[Fleet]
Disable FQDN selector by default (#152592)\n\n## Summary\r\n\r\nHide the
FQDN selector unless experimental feature is enabled. This\r\nselector
was added as part
of\r\nhttps://github.com//issues/149059\r\n\r\n###
Before:\r\n<img width=\"1073\" alt=\"Screenshot 2023-03-02 at 16 15
39\"\r\nsrc=\"https://user-images.githubusercontent.com/3315046/222487164-75024608-b0f1-419d-bbb0-299bad55cae1.png\">\r\n\r\n###
After:\r\n<img width=\"1112\" alt=\"Screenshot 2023-03-02 at 16 14
52\"\r\nsrc=\"https://user-images.githubusercontent.com/3315046/222487206-c58f76eb-6977-4d3a-908d-3b72b0f901fa.png\">\r\n\r\nCo-authored-by:
Kibana Machine
<[email protected]>","sha":"de482cbc9ebce0f6d424e90b3e98cffd9979e707"}},"sourceBranch":"main","suggestedTargetBranches":["8.7"],"targetPullRequestStates":[{"branch":"8.7","label":"v8.7.0","labelRegex":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v8.8.0","labelRegex":"^v8.8.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/152592","number":152592,"mergeCommit":{"message":"[Fleet]
Disable FQDN selector by default (#152592)\n\n## Summary\r\n\r\nHide the
FQDN selector unless experimental feature is enabled. This\r\nselector
was added as part
of\r\nhttps://github.com//issues/149059\r\n\r\n###
Before:\r\n<img width=\"1073\" alt=\"Screenshot 2023-03-02 at 16 15
39\"\r\nsrc=\"https://user-images.githubusercontent.com/3315046/222487164-75024608-b0f1-419d-bbb0-299bad55cae1.png\">\r\n\r\n###
After:\r\n<img width=\"1112\" alt=\"Screenshot 2023-03-02 at 16 14
52\"\r\nsrc=\"https://user-images.githubusercontent.com/3315046/222487206-c58f76eb-6977-4d3a-908d-3b72b0f901fa.png\">\r\n\r\nCo-authored-by:
Kibana Machine
<[email protected]>","sha":"de482cbc9ebce0f6d424e90b3e98cffd9979e707"}}]}]
BACKPORT-->

x-pack/plugins/fleet/common/experimental_features.ts

@@ -19,7 +19,7 @@ export const allowedExperimentalValues = Object.freeze({
   experimentalDataStreamSettings: false,
   displayAgentMetrics: true,
   showIntegrationsSubcategories: false,
-  agentFqdnMode: true,
+  agentFqdnMode: false,
 });
 
 type ExperimentalConfigKeys = Array<keyof ExperimentalFeatures>;