convert job_title to govuk_text_field

[starswan]

Trello card URL

https://trello.com/c/yWLaAV0C/2581-change-job-title-field-from-textarea-to-classic-text-input

Changes in this PR:

Convert job_title to text field

Screenshots of UI changes:

Before

After

Checklists:

Data & Schema Changes

If this PR modifies data structures or validations, check the following:

• Adds/removes model validations
• Adds/removes database fields
• Modifies Vacancy enumerables (phases, working patterns, job roles, key stages, etc.)

If any of the above options has changed then the author must check/resolve all of the following...

Integration Impact

Does this change affect any of these integrations?

• DfE Analytics platform
• Legacy imports mappings
• DWP Find a Job export mappings
• Publisher ATS API (may require mapping updates or API versioning)

User Experience & Data Integrity

Could this change impact:

• Existing subscription alerts (will legacy subscription search filters break?)
• Legacy vacancy copying (will copied vacancies fail new validations?)
• In-progress drafts for Vacancies or Job Applications

[github-actions]

Review app deployed to https://teaching-vacancies-review-pr-8496.test.teacherservices.cloud on AKS