Add ability to override certain variables in parentsJobPipeline via Jenkins parameters

In [parentsJobPipeline](https://github.com/adoptium/aqa-tests/blob/master/buildenv/jenkins/parentsJobPipeline.groovy) we pull information from build pipelines or set hard-coded values to populate information like JDK_IMPL, SDK_RESOURCE and PLATFORMS. We will need to be able to override these values with subset of values for them in certain cases, so we will need to be able to set them through Jenkins parameters.

Start in buildenv/jenkins/parentsJobPipeline.groovy and trace how JDK_IMPL, SDK_RESOURCE, and PLATFORMS are populated from build pipelines or hard-coded values. Review the Jenkins parameters used by this pipeline, then define what values should be overridable and verify that parameter values take effect for the relevant cases without changing the defaults.

Written by the indexing model from the issue text.