[Tokenomics] Update telemetry to include relay mining difficulty and EMA

[red-0ne]

Summary

Add RelayMiningDifficulty and Relays EMA metrics to UpdateRelayMiningDifficulty keeper function and create the corresponding Grafana charts to the stress test dashboard

A TargetNumRelays of 2 was used for the chart below.

Issue

• 626

Type of change

Select one or more:

• [x] New feature, functionality or library
• [ ] Bug fix
• [ ] Code health or cleanup
• [ ] Documentation
• [ ] Other (specify)

Testing

Documentation changes (only if making doc changes)

• [ ] make docusaurus_start; only needed if you make doc changes

Local Testing (only if making code changes)

• [x] Unit Tests: make go_develop_and_test
• [x] LocalNet E2E Tests: make test_e2e
• See quickstart guide for instructions

PR Testing (only if making code changes)

• [ ] DevNet E2E Tests: Add the devnet-test-e2e label to the PR.
  • THIS IS VERY EXPENSIVE, so only do it after all the reviews are complete.
  • Optionally run make trigger_ci if you want to re-trigger tests without any code changes
  • If tests fail, try re-running failed tests only using the GitHub UI as shown here

Sanity Checklist

• [x] I have tested my changes using the available tooling
• [x] I have commented my code
• [x] I have performed a self-review of my own code; both comments & source code
• [x] I create and reference any new tickets, if applicable
• [x] I have left TODOs throughout the codebase, if applicable

[github-actions[bot]]

The CI will now also run the e2e tests on devnet, which increases the time it takes to complete all CI checks.

You may need to run make trigger_ci to submit an empty commit that'll trigger the tests.

GCP workloads (requires changing the namespace to 631)) Grafana network dashboard for devnet-issue-{issue-id}