Set StateBackend::Transaction to PrefixedMemoryDB (#14612)

* Yep

* Try to get it working everywhere

* Make `from_raw_storage` start with an empty db

* More fixes!

* Make everything compile

* Fix `child_storage_root`

* Fix after merge

* Cleanups

* Update primitives/state-machine/src/overlayed_changes/mod.rs

Co-authored-by: Davide Galassi <davxy@datawok.net>

* Review comments

* Fix issues

* Silence warning

* FMT

* Clippy

---------

Co-authored-by: Davide Galassi <davxy@datawok.net>

substrate/utils/frame/try-runtime/cli/src/commands/follow_chain.rs

@@ -177,7 +177,6 @@ where
 		let storage_changes = changes
 			.drain_storage_changes(
 				&state_ext.backend,
-				&mut Default::default(),
 				// Note that in case a block contains a runtime upgrade, state version could
 				// potentially be incorrect here, this is very niche and would only result in
 				// unaligned roots, so this use case is ignored for now.