This commit optimizes `DefaultLifecycleProcessor::stopBeans` by using a
`TreeMap` when gathering the `LifecycleGroup`s during stopBeans. It also
switches to a functional style using `computeIfAbsent`.
Finally, it further optimizes `LifecycleGroup` by removing sorting of
`LifecycleGroupMember` members list entirely, turning the class into a
simple record.
This is possible because the members list is already comprised of
members which all share the same phase value, so sorting according to
each member's phase is redundant.
Closes gh-30361
Co-authored-by: Simon Baslé <sbasle@vmware.com>
b311088f5a