feat: Optional direct OpenMetrics scraping for both remote and within-cluster monitoring

[mattkjames7]

Allow metrics to be scraped directly from Memgraph, skipping mg-exporter entirely, for remote monitoring when using the OpenMetrics format.

Added the ability to scrape Memgraph directly within the cluster using kube-prometheus-stack and included a dashboard to view the available metrics.

[mattkjames7]

Tracking

• [Link to Epic/Issue]

Standard development

• Update / add chart templates, values, and NOTES.txt as needed
• Run helm lint and helm template locally against the changed chart(s)
• Verify the chart installs and upgrades cleanly on a test cluster

Labels checklist

• Add a docs label (exactly one): docs-changelog-only, docs-needed, or docs-not-needed
• Add at least one component label: memgraph, memgraph-ha, memgraph-lab, or infrastructure
• Add at least one type label: bug, feature, or infrastructure
• Assign the PR to a milestone
  • If not known, set for a later milestone

Documentation checklist

• Write a release note, including added/changed clauses
  • Added the scrapeMemgraphDirectly option to both standalone and HA charts so that metrics can be scraped directly from Memgraph using the OpenMetrics format for both local and remote monitoring. #254
• document direct scraping of openmetrics from Memgraph in kubernetes documentation#1662
  • Is back linked to this development PR