[filebeat][gcs] - Added retry config & refactored the default config options

[ShourieG]

Type of change

• Enhancement

Proposed commit message

• Added retry config.
• Refactored the default config options
• Updated docs accordingly and fixed some existing errors.
• Added tests.
• Removed an instance of an un-used log parameter in the fetchStorageClient method

Checklist

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

Disruptive User Impact

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Closes https://github.com/elastic/integrations/issues/11580
• Relates https://github.com/elastic/beats/issues/41107

Use cases

Screenshots

Logs

[mergify[bot]]

This pull request does not have a backport label. If this is a bug or security fix, could you label this PR @ShourieG? 🙏. For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit

[mergify[bot]]

backport-8.x has been added to help with the transition to the new branch 8.x. If you don't need it please use backport-skip label and remove the backport-8.x label.

[elasticmachine]

Pinging @elastic/security-service-integrations (Team:Security-Service Integrations)