Revert "[bridges] Prune messages from confirmation tx body, not from the on_idle" #3455

Job	Run time
set-image	10s
check-runtime-migration (asset-hub-westend)	4m 6s
check-runtime-migration (asset-hub-rococo)	31m 42s
check-runtime-migration (bridge-hub-westend)	4m 30s
check-runtime-migration (bridge-hub-rococo)	4m 40s
check-runtime-migration (contracts-rococo)	8m 52s
check-runtime-migration (collectives-westend)	4m 7s
check-runtime-migration (coretime-rococo)	4m 38s
	1h 2m 45s

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