Fix a race condition when downloading pupernetes

[L3n41c]

What does this PR do?

Fix a race condition when downloading pupernetes

Motivation

It happens that from time to time, we see failures likes this:

 waiting for pupernetes binary to be in PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/opt/bin ...
 + sudo -kE pupernetes wait --unit-to-watch pupernetes.service --logging-since 2h --wait-timeout 20m
 sudo: pupernetes: command not found
 + sleep 10
 + sudo -kE pupernetes wait --unit-to-watch pupernetes.service --logging-since 2h --wait-timeout 20m
 sudo: pupernetes: command not found
 + exit 1
Running after_script
00:01
Uploading artifacts for failed job
00:01
 ERROR: Job failed: exit code 1

Additional Notes

Anything else we should know when reviewing?