Remove/document remaining Electra TODOs #20199

Job	Run time
lockbud	15m 8s
Check for 'skip-ci' label	1s
check-code	13m 32s
check-msrv	5m 36s
target-branch-check	1s
op-pool-tests	23m 20s
release-tests-ubuntu	22m 52s
debug-tests-ubuntu	10m 54s
beacon-chain-tests	35m 0s
release-tests-windows	37m 40s
network-tests	23m 45s
slasher-tests	4m 5s
state-transition-vectors-ubuntu	8m 34s
basic-simulator-ubuntu	22m 59s
cargo-sort	15s
cargo-udeps	7m 35s
cli-check	15m 26s
compile-with-beta-compiler	14m 56s
ef-tests-ubuntu	10m 35s
execution-engine-integration-ubuntu	7m 47s
fallback-simulator-ubuntu	20m 11s
test-suite-success	3s
	5h 0m 15s

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