Prepare for rust stable 1.60 (#11138)

* Prepare for rust stable 1.59

Besides preparing the UI tests this also adds a new script update-rust-stable.sh script for
simplifying the update of a rust stable version. This script will run all UI tests for the new
rust stable version and updating the expected output.

* Ensure we run the UI tests in CI

* use staging ci image

* More test updates

* Unignore test (#11097)

* empty commit for pipeline rerun

* empty commit for pipeline rerun

* Try to make clippy happy

* More clippy fixes

* FMT

* ci image production

Co-authored-by: alvicsam <alvicsam@gmail.com>
Co-authored-by: Alexander Samusev <41779041+alvicsam@users.noreply.github.com>

substrate/utils/frame/remote-externalities/src/lib.rs

@@ -848,7 +848,7 @@ impl<B: BlockT + DeserializeOwned> Builder<B> {
 		info!(
 			target: LOG_TARGET,
 			"injecting a total of {} child keys",
-			child_kv.iter().map(|(_, kv)| kv).flatten().count()
+			child_kv.iter().flat_map(|(_, kv)| kv).count(),
 		);
 
 		for (info, key_values) in child_kv {