[MEV Boost\Builder] Add Builder Specific Metrics

[StefanBratanov]

PR Description

• Added a MetricRecordingExecutionBuilderClient similar to MetricRecordingValidatorApiChannel
• Used MetricsCountersByIntervals to track requests by method name, outcome and execution time interval
• Added executionPayloadSourceCounter in ExecutionLayerChannelImpl to track where the execution payload is coming from (local_el, builder, builder_local_el_fallback)
• Added some final here and there to ExecutionLayerManagerImplTest

Metrics look like this

# HELP beacon_builder_requests_total Counter recording the number of requests made to the builder by method, outcome and execution time interval
# TYPE beacon_builder_requests_total counter
beacon_builder_requests_total{method="get_header",outcome="SUCCESS",interval="[0,100)",} 7.0
beacon_builder_requests_total{method="get_payload",outcome="SUCCESS",interval="[0,100)",} 8.0
beacon_builder_requests_total{method="register_validators",outcome="SUCCESS",interval="[0,100)",} 1.0
beacon_builder_requests_total{method="status",outcome="SUCCESS",interval="[0,100)",} 10.0

Fixed Issue(s)

related to #5711

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[tbenr]

LGTM generally. But it would be interesting to use MetricsCountersByIntervals and we could start tracking response times on API. BN as well as engine\builder

[tbenr]

LGTM

[tbenr]

LGTM