Backport of [CC-7434] Skip collecting data directory metrics in dev mode into release/1.18.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #20521 to be assessed for backporting due to the inclusion of the label backport/1.18.

The below text is copied from the body of the original PR.

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Description

Fixes an issue where in dev mode, the data directory is not set, so this metrics collection would always fail and logs errors.

2024-02-07T14:15:06.466-0600 [ERROR] agent.host_stats: failed to collect dataDir disk stats: error="failed to collect disk usage stats: no such file or directory"
2024-02-07T14:15:16.468-0600 [ERROR] agent.host_stats: failed to collect dataDir disk stats: error="failed to collect disk usage stats: no such file or directory"
2024-02-07T14:15:26.468-0600 [ERROR] agent.host_stats: failed to collect dataDir disk stats: error="failed to collect disk usage stats: no such file or directory"

Testing & Reproduction steps

Checked that metrics were skipped in dev mode:

1. Started consul in dev mode (consul agent -dev)
2. Inspected the logs to ensure this error was no longer outputted

Checked that metrics were collected otherwise:

1. Started Consul in server mode and not dev mode (consul agent -server)
2. Fetched the agent metrics (/v1/agent/metrics) and checked that there were data directory metrics:

...
        {
            "Name": "consul.mkam-host.host.disk.available",
            "Value": 135710160000,
            "Labels": {
                "path": ".mkam/data-dir"
            }
        },
        {
            "Name": "consul.mkam-host.host.disk.inodes_percent",
            "Value": 0.44313493,
            "Labels": {
                "path": ".mkam/data-dir"
            }
        },
...

Links

https://hashicorp.atlassian.net/browse/CC-7434

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

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Overview of commits

• 5d591bb - cdfb10b

[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR