WIP: Do not use sanitize in url_blocker

What does this MR do?

During the secure development training, it was recommended not to use the Rails sanitize method due to the large number of CVEs that are regularly reported.

This MR removes the usage of sanitize in url_blocker.rb. Instead, it checks to make sure that no special characters are present in the URL by encoding the URL and comparing the URL string before and after encoding.

CE MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/32153

Screenshots

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