feat: TLS config and fix mg-exporter TLS configuration

[as51340]

Breaking because of bolt TLS change.
Relies on memgraph exporter 0.2.3 working.

[as51340]

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
  • TLS for bolt server can now be set-up using tls.bolt.enabled flag and K8s secret. User must not set manually --bolt-cert-file and --bolt-key-file because chart auto-appends that flag. #246
  • What has changed? What does it mean for a user? What should a user do with it? [#{{PR_number}}]({{link to the PR}})
• Documentation PR link
  • Is back linked to this development PR

[github-actions]

Release note advisory

TLS for bolt server can now be set-up using tls.bolt.enabled flag and K8s secret. User must not set manually --bolt-cert-file and --bolt-key-file because chart auto-appends that flag. #246

The note contains two sentences instead of the required single sentence; please merge into one concise sentence (and clarify wording like 'that flag' → 'those flags').