Don't import pull request comments from Gitea repos

What does this MR do?

Fixes #63071 (closed)

The Gitea API does not provide the following API endpoint for pull request comments:

/api/v1/repos/{owner}/{repo}/pulls/comments

When the importer attempts to request this endpoint it receives a '404 Not Found' error which causes the import to fail. By skipping any attempts to import pull requests comments from Gitea we can ensure that the import can complete successfully.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team