scylla-node: remove ignore_errors, make node exporter from 2022 work

[tarzanek]

2022 node exporter now works for clean install and upgrades

fix detection of node-exporter services

make sure the name of node exporter service matches the check

[tarzanek]

I split away node exporter from #232

can you review @vladzcloudius or @igorribeiroduarte / @ebenzecri ?

[tarzanek]

don't merge, I am trying to fix molecule

[tarzanek]

ok, molecule should pass now
@igorribeiroduarte @vladzcloudius this is just extract of reviewed and tested commit from #232

so please re-review, or check above, this will get rid of ignore errors for node exporter and properly use it for any Scylla version now

[tarzanek]

@vladzcloudius ping?

[vladzcloudius]

This PR has conflicts, please, rebase.

[tarzanek]

rebased, but logic changed, I need to retest new condition

  when: (install_type == 'online') and (node_exporter_install.stat.exists) and ((scylla_package_prefix + '-node-exporter') not in ansible_facts.packages)

[tarzanek]

so basically classic situation when you have old 2021 Scylla and you upgrade needs to be retested with this new change