Summary: If vm.swappiness is already set in sysctl.conf, we should replace the line in file (because it could have incorrect value)

Test Plan: provision instance with vm.swappiness=1 in cofigs

Reviewers: anijhawan, vkumar

Reviewed By: vkumar

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D46978