Fix CI failure

[batmat]

(Edited description after the fact, for better up-front clarity)

For some unclear reason iI did not spend hours investigating, #58 PR was green. BUT the master branch started failing when it got merged.

The reason is that the jenkins.version in one combinatorial of recommendedConfiguration (2.164, which is older than jenkins.version of the metrics-plugin currently).is more

This PR is fixing the Jenkinsfile by "exploding" the recommendedConfiguration with the various axis to be tested. This way we have control on the LTS to use (and it's bumped to the one declared in the pom.xml).

[alecharp]

I know what's happening. https://github.com/jenkins-infra/pipeline-library/blob/376e4789fcfca012198fd2dccba7436db87b3a36/vars/buildPlugin.groovy#L310 is forcing the version of the plugin to use Jenkins Core 2.164.1 even though this plugin is using 2.222.1 (https://github.com/jenkinsci/metrics-plugin/blob/master/pom.xml#L68). Checking if there is a INFRA issue to track that.

[alecharp]

I just created https://issues.jenkins.io/browse/INFRA-2798

[batmat]

What I don't really get is why #58 was green when a PR, but failed when merged.

We want to drive this, or "explode" the recommended configurations here directly to move forward.
There has been multiple attemps to evolve recommendedConfigurations (I personally quite pushed back against some of the attempts), to no avail until now.

[batmat]

Confirmed, windows build is the only one failing.