Vue 3 migration: ZenTao entry points

Summary

Migrate the following ZenTao page entrypoints to Vue 3 as part of gitlab-org&23066.

Entrypoints

• pages.projects.integrations.zentao.issues.index
• pages.projects.integrations.zentao.issues.show

Migration steps

Follow the Vue 3 migration guide for each entrypoint:

1. Add a vue3_migration.yml sibling file with status: rollout
2. Create a feature flag and rollout issue
3. Once rolled out globally, flip to status: migrated and remove the flag