Add OS usage data (including pretty_name) to Core usage data

[joshdover]

In #79101 we added Core usage data but didn't move OS data. We should also remove the existing OS usage data in the kibana_stats usage collector.

Elasticsearch telemetry collects more human readable OS information that allows for easier processing and analysis.

Let's duplicate this collection strategy to enhance our OS telemetry data that was added in #21978

[elasticmachine]

Pinging @elastic/kibana-operations

[LeeDr]

Here's some sample data showing the Elasticsearch data and the Kibana data. To avoid breaking any existing Saved searches, visualizations, or dashboards we should consider leaving the existing stack_stats.kibana.os.platformReleases and stack_stats.kibana.os.platforms fields as they are and maybe just add a new stack_stats.kibana.os.pretty_names field like the cluster_stats.nodes.os.pretty_names for Elasticsearch.

| cluster_stats.nodes.os.names | cluster_stats.nodes.os.pretty_names |
stack_stats.kibana.os.platformReleases | stack_stats.kibana.os.platforms |
|------------|------------|-------|------|
| { "name": "Linux", "count": 1 } | { "pretty_name": "CentOS Linux 7 (Core)", "count": 1 } | { "count": 1, "platformRelease": "linux-4.4.74-1.ph1-esx" } | { "count": 1, "platform": "linux" } |
| { "name": "Linux", "count": 1 } | { "pretty_name": "Ubuntu 14.04.3 LTS", "count": 1 } | { "count": 1, "platformRelease": "linux-4.15.0-1027-aws" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 1 } | { "pretty_name": "Ubuntu 16.04.6 LTS", "count": 1 } | { "count": 1, "platformRelease": "linux-4.4.0-154-generic" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 12 } | { "pretty_name": "Debian GNU/Linux 9 (stretch)", "count": 12 } | { "count": 1, "platformRelease": "linux-4.4.0-97-generic" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 3 } | { "pretty_name": "Ubuntu 14.04.3 LTS", "count": 3 } | { "count": 1, "platformRelease": "linux-4.15.0-1027-aws" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 9 } | { "pretty_name": "Ubuntu 18.04.2 LTS", "count": 9 } | { "count": 1, "platformRelease": "linux-4.18.0-1023-azure" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 1 } | { "pretty_name": "Amazon Linux 2", "count": 1 } | { "count": 1, "platformRelease": "linux-4.14.88-88.76.amzn2.x86_64" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 2 } | { "pretty_name": "Ubuntu 14.04.3 LTS", "count": 2 } | { "count": 1, "platformRelease": "linux-4.15.0-1027-aws" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 1 } | { "pretty_name": "Ubuntu 14.04.6 LTS", "count": 1 } | { "count": 1, "platformRelease": "linux-3.13.0-165-generic" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 31 } | { "pretty_name": "Red Hat Enterprise Linux Server 7.6 (Maipo)", "count": 31 } | { "count": 4, "platformRelease": "linux-3.10.0-957.21.3.el7.x86_64" } | { "count": 4, "platform": "linux" }
| { "name": "Linux", "count": 76 } | { "pretty_name": "CentOS Linux 7 (Core)", "count": 76 } | { "count": 1, "platformRelease": "linux-3.10.0-862.6.3.el7.x86_64" }, { "count": 1, "platformRelease": "linux-3.10.0-862.3.2.el7.x86_64" } | { "count": 2, "platform": "linux" }
| { "name": "Linux", "count": 1 } | { "pretty_name": "Debian GNU/Linux 9 (stretch)", "count": 1 } | { "count": 1, "platformRelease": "linux-4.9.0-9-amd64" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 13 } | { "pretty_name": "CentOS Linux 7 (Core)", "count": 13 } | { "count": 1, "platformRelease": "linux-4.14.109-99.92.amzn2.x86_64" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 4 } | { "pretty_name": "Ubuntu 14.04.3 LTS", "count": 4 } | { "count": 1, "platformRelease": "unknown" } | { "count": 1, "platform": "unknown" }
| { "name": "Linux", "count": 2 } | { "pretty_name": "Red Hat Enterprise Linux Server 7.6 (Maipo)", "count": 2 } | { "count": 1, "platformRelease": "darwin-18.6.0" } | { "count": 1, "platform": "darwin" }
| { "name": "Linux", "count": 14 } | { "pretty_name": "CentOS Linux 7 (Core)", "count": 14 } | { "count": 1, "platformRelease": "linux-3.10.0-957.12.1.el7.x86_64" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 3 } | { "pretty_name": "CentOS Linux 7 (Core)", "count": 3 } | { "count": 1, "platformRelease": "linux-4.14.106-79.86.amzn1.x86_64" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 1 } | { "pretty_name": "Red Hat Enterprise Linux Server 7.6 (Maipo)", "count": 1 } | { "count": 1, "platformRelease": "linux-3.10.0-957.el7.x86_64" } | { "count": 1, "platform": "linux" }
| { "name": "Linux", "count": 45 } | { "pretty_name": "CentOS release 6.5 (Final)", "count": 45 } | { "count": 1, "platformRelease": "linux-2.6.32-696.30.1.el6.centos.plus.x86_64" } | { "count": 1, "platform": "linux" }