T6630: ntp: fix timestamp nested under ptp

[lucasec]

Change Summary

This PR updates the ntp feature so that timestamp is not placed under ptp. These are independent features.

This was the intended original behavior of #3966 but it was modified during review alongside some other config syntax style changes. The merged docs PR described the expected final syntax: vyos/vyos-documentation#1553. This updates the code to match the docs.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

https://vyos.dev/T6630

Related PR(s)

Component(s) name

service ntp

Proposed changes

How to test

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[github-actions]

👍
No issues in PR Title / Commit Title

[github-actions]

CI integration ❌ failed!

Details

CI logs

• CLI Smoketests (no interfaces) 👍 passed
• CLI Smoketests (interfaces only) ❌ failed
• Config tests 👍 passed
• RAID1 tests 👍 passed
• TPM tests 👍 passed

[c-po]

New/experimental feature - no migration required