Migrating polkadot-runtime-parachains configuration benchmarking to V2 (#6607)

# Description
Migrating polkadot-runtime-parachains configuration benchmarking to the
new benchmarking syntax v2.
This is a part of #6202

---------

Co-authored-by: Giuseppe Re <giuseppe.re@parity.io>
Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: seemantaggarwal <32275622+seemantaggarwal@users.noreply.github.com>