Support regex in ignore_metrics

[shachar-ash]

Description

Currently, when metrics are excluded and we want to add an exception for a subset of metrics, the only option is to add an exception for a prefix.

This is a problem, as it forces us to keep metrics we don't necessarily want. For example, let's look at the following rules:

               ignore_metrics:
                  - prefixes:
                    - 'envoy_'
                    except:
                      - 'envoy_cluster_external_upstream_rq'

In the above example, the only metric I want to keep is envoy_cluster_external_upstream_rq, but when adding this except clause, I am also forced to keep every other metric with the prefix envoy_cluster_external_upstream_rq, so I'll end up having other metrics I don't want, like envoy_cluster_external_upstream_rq_time for example.

Acceptance Criteria

Add regex support, instead of only supporting metrics prefixes.

Estimates

T-shirt size: S = 1-3 days

[workato-integration]

https://new-relic.atlassian.net/browse/NR-232744