Stream timeout with asset issuances

[DerpHerpenstein]

The api seems to be having issues with asset issuances at the moment.

https://api.counterparty.io:4000/v2/addresses/bc1qy25gwr9vdrvxx0w35wa9vrpc3hc5h6rd0p56f4/compose/issuance?asset=A12590236770677120000&quantity=1&divisible=false&lock=true&description=STAMP%3A&exact_fee=15095&return_psbt=true

[adamkrellenstein]

Yeah Bitcoin Core is overloaded because we're updating some nodes. We need to migrate to using electrs for initial mempool synchronization because it's not single-threaded for RPC. Cf. #2837 and #2843