Add poller last triggered block metric and improve block number handling

[iuwqyir]

TL;DR

Added a new metric for the last triggered block in the poller and improved block number tracking.
Removed the division by 10, because this should be configured in Grafana settings to not display scientific notation

What changed?

• Introduced a new Prometheus gauge metric poller_last_triggered_block to track the last block number that triggered the poller.
• Updated the Poller.Start() method to set the new metric with the end block number of each polling cycle.
• Modified the Worker.Run() method to use Float64() instead of dividing by 10 when setting the LastFetchedBlock metric, addressing a TODO and improving precision.

How to test?

1. Run the application and ensure it starts without errors.
2. Check Prometheus metrics to verify the new poller_last_triggered_block metric is present and updating correctly.
3. Confirm that the LastFetchedBlock metric is now reporting accurate values without scientific notation.

Why make this change?

• The new poller_last_triggered_block metric provides better visibility into the poller's progress, allowing for more accurate monitoring and debugging.
• Updating the LastFetchedBlock metric calculation improves precision and removes the need for the temporary division workaround, enhancing the overall reliability of the metrics system.

[iuwqyir]

• Add poller last triggered block metric and improve block number handling #86 👈
• main

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