Problem/Motivation
instead of using a StorageComparer as proposed in #3223976: Use StorageComparer in StorageCopyTrait we can just optimise the order of operations in StorageCopyTrait to use less write operations in the stroage. (ie by writing only what changed) Of course this is a tradeoff because it involves reading everything, but often that is faster.
Steps to reproduce
see #3217783: Configuration management performance regression - slow config:import
Proposed resolution
Do not delete all before writing everything again and instead delete only what needs to be deteled and write only what changed.
Remaining tasks
patch review merge party
User interface changes
none
API changes
none
Data model changes
none
Release notes snippet
tbd