Update MobSF to 3.4.6

What does this MR do?

Update MobSF to v3.4.6.

There were enough changes, including severity values and similar changes, that it seemed prudent to update to v3.4.6 separately from v3.5.0.

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/security-products/release/-/issues/118

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer