Change API Security port number to 5000

What does this MR do?

Change the scanner service port to 5000 instead of 80. This work supports moving our container to run as a non-root user.

Relates to #287702 (closed)

CI Template

1. The API Fuzzing CI template is not versioned yet (less than 1yr old).
2. This change is backwards compatible. The existing port 80 will continue to work.
3. No tests have been updated. The CI template logic hasn't changed, so no tests need updating.
4. Test project:
   1. Project is here
   2. Template is here
   3. Job is here

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability 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
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

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

Related to #287702 (closed)