[8.6](backport #34014) x-pack/filebeat/input/{cel,httpjson}: make transport keep-alives configurable

[mergify]

This is an automatic backport of pull request #34014 done by Mergify.
Cherry-pick of 3cd8d81 has failed:

On branch mergify/bp/8.6/pr-34014
Your branch is up to date with 'origin/8.6'.

You are currently cherry-picking commit 3cd8d811d6.
  (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-cel.asciidoc
	modified:   x-pack/filebeat/docs/inputs/input-httpjson.asciidoc
	modified:   x-pack/filebeat/input/cel/config.go
	modified:   x-pack/filebeat/input/cel/config_test.go
	modified:   x-pack/filebeat/input/httpjson/config_request.go
	modified:   x-pack/filebeat/input/httpjson/config_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   x-pack/filebeat/input/cel/input.go
	both modified:   x-pack/filebeat/input/httpjson/input.go
	both modified:   x-pack/filebeat/input/httpjson/request_chain_helper.go

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

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• Start Time: 2023-01-18T23:16:05.396+0000

• Duration: 75 min 6 sec

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Total	2720

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