Add missing shebang to vrrp_script

The shebang is missing from files/vrrp_script.sh which is used as
a default template for custom check scripts. In the 1.x version it had
no matter but the 2.x versions do not allow this.

Closes-Bug: PROD-35635
Change-Id: I708d7a45b2df570d2a6375ee58e67a0b1b4ed59c
2 files changed