ipsec: T6148: Removed unused imports (backport #3915)

[mergify]

Change Summary

It is a cosmetic change.
Removed unused pprint module

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/T6148

Related PR(s)

Component(s) name

ipsec

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

---

This is an automatic backport of pull request #3915 done by [Mergify](https://mergify.com).

[github-actions]

👍
No issues in PR Title / Commit Title

[github-actions]

❌
warning: Unused import os in smoketest/scripts/cli/test_interfaces_l2tpv3.py:17.warning: Unused directories imported from vyos.defaults in src/conf_mode/system_console.py:25.warning: Unused import pprint in src/op_mode/ipsec.py:16.