Improve `try-runtime::on_runtime_upgrade` and fix some storage version issues (#14083)

We now run all `try_on_runtime_upgrade` and collect the errors, instead of bailing on the first
error. This makes it easier to see directly all the things that are failing instead of fixing one,
recompiling and then checking the next one.

Then this pr also sets the correct storage version for `pallet-bounties` that was already correctly
set in the storage with the appropriate migration.