[WIP] Drop HeadTracker #128

Job	Run time
cargo-udeps	6m 18s
beacon-chain-tests	10m 22s
check-code	4m 25s
check-msrv	4m 5s
cli-check	13m 32s
compile-with-beta-compiler	8m 47s
debug-tests-ubuntu	7m 18s
dockerfile-ubuntu	8m 43s
doppelganger-protection-test	10m 59s
eth1-simulator-ubuntu	10m 48s
execution-engine-integration-ubuntu	13m 48s
ef-tests-ubuntu	10m 22s
merge-transition-ubuntu	10m 29s
network-tests	4m 36s
no-eth1-simulator-ubuntu	4m 14s
op-pool-tests	10m 5s
release-tests-ubuntu	11m 30s
release-tests-windows	17m 12s
slasher-tests	2m 22s
state-transition-vectors-ubuntu	12m 11s
syncing-simulator-ubuntu	6m 41s
target-branch-check	1s
test-suite-success	0s
	3h 8m 48s

Provide feedback