[8.15](backport #40601) [filebeat][streaming] - Added retry functionality to websocket connections

[mergify]

Type of change

Please label this PR with one of the following labels, depending on the scope of your change:

• Enhancement
• Docs

Proposed commit message

Added retry functionality to websocket connections under the streaming input. Docs & tests have been updated accordingly to support the new functionality.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
  - [ ] I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Disruptive User Impact

None

Author's Checklist

How to test this PR locally

Related issues

• Closes [filebeat][websocket] - Add retry mechanism to socket connections #40271

Use cases

Screenshots

Logs

---

This is an automatic backport of pull request #40601 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 0c3c9c6 has failed:

On branch mergify/bp/8.15/pr-40601
Your branch is up to date with 'origin/8.15'.

You are currently cherry-picking commit 0c3c9c6e65.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   CHANGELOG.next.asciidoc
	modified:   x-pack/filebeat/docs/inputs/input-websocket.asciidoc
	modified:   x-pack/filebeat/input/websocket/config.go
	modified:   x-pack/filebeat/input/websocket/config_test.go
	modified:   x-pack/filebeat/input/websocket/input_test.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   x-pack/filebeat/input/streaming/websocket.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[botelastic]

This pull request doesn't have a Team:<team> label.

[ShourieG]

The structure of the websocket input changed from 8.15 to 8.16 to evolve into a more generic streaming input, hence this backport is not possible without merging the refactor.