Remove pattern validation for service number

[TaiWilkin]

Are you removing, renaming or moving a folder in this PR?

• No, I'm not changing any folders (skip to Summary and delete the rest of this section)
• Yes, I'm removing, renaming or moving a folder

Summary

Removes the pattern validation for Pensions service number to allow both the old format for service number and SSN.

Related issue(s)

• Remove field validation on Military Service Number va.gov-team#90673

Testing done

• Navigate to the service branches page in Pensions
• Add any string in the service number field and confirm it's accepted

Screenshots

What areas of the site does it impact?

Pensions

Acceptance criteria

Quality Assurance & Testing

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Linting warnings have been addressed
• Documentation has been updated (link to documentation *if necessary)
• Screenshot of the developed feature is added
• Accessibility testing has been performed

Error Handling

• Browser console contains no warnings or errors.
• Events are being sent to the appropriate logging solution
• Feature/bug has a monitor built into Datadog or Grafana (if applicable)

Authentication

• Did you login to a local build and verify all authenticated routes work as expected with a test user

[mjknight50]

GTG