Add counters to Pablo's integration of the defensive mempool

[nfrisby]

Description

Adding EKG metrics for the soft and hard timeouts in the new defensive mempool feature.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Runnings tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-9.6 and ghc-9.12
• Self-reviewed the diff

Note on CI

If your PR is from a fork, the necessary CI jobs won't trigger automatically for security reasons.
You will need to get someone with write privileges. Please contact IOG node developers to do this
for you.

[nfrisby]

@mgmeier Does this look like a sufficient way to add new EKG counters?

[nfrisby]

As of the current tip, cabal build exe:cardano-node lib:cardano-tracer -f+rtview builds clean for me. cabal build all does not, but I assume Pablo just hasn't finished yet on the defensive-mempool branch that this PR targets.

[mgmeier]

An additional word about RTView: We are not aware of any active users of that feature, and it's not shipped with our releases of cardano-tracer. The. README states that we only "guarantee it remains buildable and usable in its current state." This means no new features or changes, as we can't sensibly go through UI/UX and e2e testing with RTView, given its design.

The new metrics this PR implements will - without any change to trace-dispatcher or cardano-tracer - be visible both on the Node's internal PrometheusSimple backend and cardano-tracer's Prometheus and EKG endpoints (new tracing) and the regular internal metrics server (legacy tracing).

[mgmeier]

The new metrics implementation LGTM! Thank you @nfrisby.