vrrp: keepalived: T2720: adjust to Jinja2 trim_blocks feature

This is a successor to commit a2ac9fac16e ("vyos.template: T2720: always enable
Jinja2 trim_blocks feature"). It only shifts the whitespaces / indents inside
the keepalived configuration file.

(cherry picked from commit c1ac0630cfe0ee65569fbe435cc006ade20fed22)