Update minimum verifier set size

Description

This proposal will temporarily set a lower minimum number of Verifiers required by the service currently used by all Amplifier blockchain connections. If approved, this change would support faster and more efficient chain onboarding – by allowing Verifiers to add chain support progressively on blockchains where node configuration may be relatively complicated. https://community.axelar.network/t/rfc-on-a-proposal-to-temporarily-lower-new-chain-verifier-threshold/3357