Summary:
Original commit: 960546c77846d3afbf69d9bae84df4adb2854c1a / D43705
In clock-sync.sh, we need the var PYTHON_EXECUTABLE set when checking
for ntpd service.

Test Plan: itest

Reviewers: muthu, yash.priyam, svarshney

Reviewed By: yash.priyam

Differential Revision: https://phorge.dev.yugabyte.com/D43731