sysctl job disables ipv6 implicitly on jammy stemcells

[fmoehler]

When adding the sysctl job it reapplies all sysctls in its pre-start script. This leads to issues when running on a jammy stemcell and using ipv6.

The jammy stemcell comes with disabled ipv6 by default. It can be enabled via config property. However this leads to the following scenario:

1. Agent enables IPv6 according to the config property
2. The os-conf-releases's sysctls pre-start script gets called which reapplys all sysctls.
3. The sysctl placed into /etc/sysctl.d by the stemcell implicitly gets reapplied disabling ipv6 again.

[fmoehler]

Fixed with cloudfoundry/bosh-agent#347