Handle 404's for PuppetDB metrics

[jarretlavallee]

Describe the Bug

There are three counters that do not exist until there is an error. This causes 3 errors in each PuppetDB request unless there is an error in PuppetDB that creates the counter exists.

Expected Behavior

There should only be errors in the output when there is something wrong. These errors show up every time, which skews the error counters. The 404's should be properly handled for the counters so they are not included in the metrics.

Steps to Reproduce

Classify a 2019.8.0 master with the class and notice the errors below.

                "error": [
                    "HTTP Error 404 for puppetlabs.puppetdb.mq:name=global.generate-retry-message-time",
                    "HTTP Error 404 for puppetlabs.puppetdb.mq:name=global.retry-persistence-time",
                    "HTTP Error 404 for puppetlabs.puppetdb.ha:name=failed-request-counter"
                ],
                "error_count": 3,

Environment

6.1.1 with 2019.8.4

https://github.com/puppetlabs/puppetlabs-puppet_metrics_collector/blob/master/manifests/service/puppetdb.pp#L31-L35
https://github.com/puppetlabs/puppetlabs-puppet_metrics_collector/blob/master/manifests/service/puppetdb.pp#L51-L55
https://github.com/puppetlabs/puppetlabs-puppet_metrics_collector/blob/master/manifests/service/puppetdb.pp#L290-L294