Fix Flaky Snippet Specs - Remove after deletion

What does this MR do and why?

Issue: #378697 (closed)

We've encountered a lot of failures with the same error message:

Failure/Error: snippet.remove_via_api!

QA::Resource::Errors::ResourceNotDeletedError:
  Resource at https://pre.gitlab.com/api/v4/snippets/7026?private_token=[****] could not be deleted (400): `{"message":{"error":"Failed to remove snippet."}}`.
  Correlation Id: 425c021672652cda9e1bb2457df1b42d
  Sentry Url: https://sentry.gitlab.net/gitlab/pregitlabcom/?environment=pre&query=correlation_id%3A%22425c021672652cda9e1bb2457df1b42d%22

As suggested by Anastasia, we can just remove this after block since we have scheduled resource cleanup now.

How to set up and validate locally

Verify: qa/qa/specs/features/browser_ui/3_create/snippet/create_project_snippet_with_multiple_files_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/add_comment_to_snippet_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/add_file_to_snippet_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/copy_snippet_file_contents_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/create_personal_snippet_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/create_personal_snippet_with_multiple_files_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/create_project_snippet_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/delete_file_from_snippet_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/share_snippet_spec.rb qa/qa/specs/features/browser_ui/3_create/snippet/snippet_index_page_spec.rb

Still pass locally.

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