Update Substrate/Polkadot refs for latest BEEFY + xcm-v3 capability (#1381)

* Update Substrate/Polkadot xcm-v3-capable references

Branches below are based on gav-xcm-v3 + cherry-picked BEEFY commits.

polkadot: 'locked-for-gav-xcm-v3-and-bridges#6e00638f0a2d07ba3bb1c7430a539c15b5a79b74'
substrate: 'sv-locked-for-gav-xcm-v3-and-bridges#a42bef088f173f54aba152ca63eb301ba44dd339'

Signed-off-by: acatangiu <[email protected]>

* millau: reduce beefy min block delta to 2

* bump substrate, polkadot refs to include beefy fixes

* grafana: fix beefy dashboards