Clean-up empty overrides (ValidatorTimingChannel)

[StefanBratanov]

PR Description

We do empty overrides for ValidatorTimingChannel which is just empty code, so cleaning it up

Fixed Issue(s)

N/A

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.

[zilm13]

LTGM

I'd not that

AttestationDutySchedulerTest covers both sides of the guard in AbstractDutyScheduler.onAttestationAggregationDue
(validator/client/src/main/java/tech/pegasys/teku/validator/client/AbstractDutyScheduler.java:171):

• shouldNotProcessAggregationIfCurrentEpochIsTooFarBeforeSlotEpoch (AttestationDutySchedulerTest.java:316) — current epoch 0, slot in epoch lookAhead+1 → verify(scheduledDuties,
  never()).performAggregationDuty(slot).
• shouldProcessAggregationIfCurrentEpochIsAtBoundaryOfLookaheadEpoch (:338) — last slot still within the window → duty performed. So the boundary is pinned on both sides.
• shouldNotProcessAggregationIfEpochIsUnknown (:302) — the currentEpoch.isEmpty() branch of isSlotTooFarAhead.