fleet coord hosts: a CreateFleet retry after a lost answer can carry a different instance type #1329

From the review of #1328. If a CreateFleet succeeds but its answer is lost, and the host template's instance type changes and the 5-minute type cache expires before the retry, the retry sends a different InstanceType with the original ClientToken and EC2 answers IdempotentParameterMismatch. reconcile() keeps the token on errors, so that region launches nothing until a restart or power change. Fix: keep the request parameters with the pending token and resend them unchanged, or drop the token on IdempotentParameterMismatch.