This PR removes a few hundred thousand temporary seq allocations during
state transition - in particular, the flag seq was allocated per
validator while committees are computed per attestation.
* require sync committee supermajority in CI
To better catch problems with sync committee messages in CI, extend
local testnet simulation to also verify that each block is signed
by a supermajority of the sync committee.
Requires #5083 and #5084
* lint
Jacek Sieka
Etan Kissling
tersec
henridf