Update Memgraph OpenMetrics dashboards

[mattkjames7]

Fixes plots for metrics with the _total suffix to use a running sum so that they increase monotonically across restarts.

[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
  • Updated OpenMetrics dashboard to use a running sum on counters (metrics with the _total suffix). #256
• [ Documentation PR link memgraph/documentation#XXXX ]
  • Is back linked to this development PR