Skip flaky tests TestFileWatcher and TestGroup_Go

[belimawr]

Proposed commit message

This PR skips two flaky tests from the Filestream input, the tests are:

• TestFileWatcher (issue: TestFileWatcher/does_not_emit_events_for_empty_files/emits_a_create_event_once_something_is_written_to_the_empty_file #41209)
• TestGroup_Go (issue: TestGroup_Go - not all goroutines finished/"task.Group: semaphore acquire failed, was the task group closed? err: context canceled #41218)

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
## Author's Checklist
## How to test this PR locally

Related issues

• Relates TestFileWatcher/does_not_emit_events_for_empty_files/emits_a_create_event_once_something_is_written_to_the_empty_file #41209
• Relates TestGroup_Go - not all goroutines finished/"task.Group: semaphore acquire failed, was the task group closed? err: context canceled #41218

## Use cases
## Screenshots
## Logs

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @belimawr? 🙏.
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]

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.

[belimawr]

I've enabled auto merge.