Follow up work on `TransactionExtension` - fix weights and clean up `… #8812

Job	Run time
preflight / preflight	14s
preflight / ci-versions	1m 9s
build (polkadot-availability-recovery, availability-recovery-regression-bench)	7m 38s
build (polkadot-availability-distribution, availability-distribution-regression-bench)	5m 16s
build (polkadot-node-core-approval-voting, approval-voting-regression-bench)	22m 34s
build (polkadot-statement-distribution, statement-distribution-regression-bench)	4m 12s
publish-benchmarks	3m 39s
	44m 42s

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