Review when to send FCU in gloas

[nflaig]

this is not needed for alpha.5 we relay on shouldExtendPayload() instead see #9209

#9164 (comment) this should still be relevant, we can't always send the FCU at 8 seconds into the slot anymore since the payload may arrive later, my gut feeling is that 10 seconds in the right number or as soon as we have enough PTC votes, but nothing that's critical for the devnet

Originally posted by @nflaig in #9164 (comment)

[nflaig]

need to review when we call this.executionEngine.notifyForkchoiceUpdate in gloas

[nflaig]

related to this, we need to review when to emit payload_attributes in gloas, we might wanna do it twice per slot in some cases (if PTC votes against payload being available)