fix: service file should not include configuration

[giem-git]

Which issue(s) this PR fixes

Fixes #96

Agreements

• I hereby declare this contribution to be licensed under the Apache License Version 2.0, January 2004.
• I hereby agree to grant TOSIT a copyright license to use my contributions.

[kpgtek]

Prometheus could not start, and I found the following error in log file:

caller=web.go:553 level=info component=web msg="Start listening for connections" address=0.0.0.0:9090
caller=main.go:792 level=error msg="Unable to validate web configuration file" err="failed to load X509KeyPair: open /etc/prometheus/certs/[...].pem: permission denied"

If I change .key and .pem files' permission to [root:hadoop], the error is fixed.

Error fixed with the commit de14e8d.