build: T7399: remove the APT option to allow downgrades

[dmbaturin]

Change summary

There was a concern about TACACS+ libs, but the change doesn't affect them — correct versions are installed.

vyos@vyos:~$ dpkg -l | grep tacplus
ii  libnss-tacplus                   1.0.4-cl5.1.0u11.1               amd64        NSS module for TACACS+ authentication without local passwd entry
ii  libpam-tacplus                   1.4.3-cl5.1.0u5                  amd64        PAM module for using TACACS+ as an authentication service
ii  libtacplus-map1                  1.0.1-cl5.1.0u9                  amd64        Library for mapping TACACS+ users without local /etc/passwd entries

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): internal change.

Related Task(s)

Related PR(s)

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• 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

[sever-sever]

Discussed at the meeting.
I do not see any harm in removing this option

[c-po]

Local build and tests run fine