Inside PrometeusHelper and PrometheusImporter PROMETHEUS_TOKEN is set from environment variable and used as authz token for Prometheus connection (only for PrometeusHelper).

This helper class is used only in local and ephemeral testing to connect with locally deployed Prometheus instance.

We don't currently have an authorization mechanism for local Prometheus, so the token is useless and confusing.

All usages are:

1. https://gitlab.cee.redhat.com/insights-qe/iqe-rhsm-subscriptions-plugin/blob/master/iqe_rhsm_subscriptions/rhsmlib/prometheus_importer.py
2. https://gitlab.cee.redhat.com/insights-qe/iqe-rhsm-subscriptions-plugin/-/blob/master/iqe_rhsm_subscriptions/rhsmlib/prometheus.py#L15
3. https://gitlab.cee.redhat.com/insights-qe/iqe-rhsm-subscriptions-plugin/-/blob/master/iqe_rhsm_subscriptions/rhsmlib/prometheus.py#L20

Acceptance criteria:

• Evaluate the deletion impact of every occurrence of PROMETHEUS_TOKEN inside iqe-rhsm-subscription-plugin is safe.
• Remove the occurrences of PROMETHEUS_TOKEN from the test base.