This is a partial backport of core#25648
Combine datacarrier globals into one
https://github.com/bitcoin/bitcoin/pull/25648/commits/fa2a6b8516b24d7e9ca11926a49cf2b07f661e81
Pass datacarrier setting into IsStandard
https://github.com/bitcoin/bitcoin/pull/25648/commits/fad0b4fab849eb5f1f0aa54ebc290f85a473ec91
Remove global
https://github.com/bitcoin/bitcoin/pull/25648/commits/66664384a6fec39ecb4d8d06db66a4f193a06e33
Notable differences from the source material:
- we already removed ::nMaxDatacarrierBytes in D1419
- the avalanche code also relies on IsStandard for verifying proofs. Wrap the function call to use MAX_OP_RETURN_RELAY in this context, to avoid having relay policies from the local node impact other nodes' proof validity
Depends on D15780