fix: restore old behavior in deprecation

[enspandi]

Description

This is a fix for the deprecation @ https://deprecations.emberjs.com/ember-data/v5.x/#toc_ember-data-deprecate-relationship-remote-update-clearing-local-state

In the case of a remote update with a local change, I think we want to have the remote state as the local state in the old way.

@runspired Does this make sense? Just encountered this issue in our upgrade from v4 => v5. Perhaps this is a copy/paste issue from the deprecation warning in line #89...

---

In v4 we run into this branch:

https://github.com/emberjs/data/blob/v4.12.7/packages/graph/src/-private/graph/operations/replace-related-record.ts#L131

if (localState !== remoteState) {
  relationship.localState = remoteState;

In v5 we run into this branch:

if (localState !== remoteState && localState === existingState) { // <-- Does not apply as we have a local mutation
  relationship.localState = remoteState;
  notifyChange(graph, relationship.identifier, relationship.definition.key);
} else if (DEPRECATE_RELATIONSHIP_REMOTE_UPDATE_CLEARING_LOCAL_STATE) {
  if (
    localState !== remoteState &&
    localState !== existingState &&
    relationship.definition.resetOnRemoteUpdate !== false
  ) {
    relationship.localState = existingState; // <-- Should be remoteState?

https://github.com/emberjs/data/blob/v5.3.3/packages/graph/src/-private/operations/replace-related-record.ts#L168

---

Example:

We change a relationship from record "1" to "null" and on save, the server returns a record "99" for this relationship.

In v4 and v5 we have the following state:

// Before the local change it was '1'
existingState.id; // = '1';

// Local change clears the relationship
relationship.localState; // = null;

// Remote wants to set '99'
op.value.id; // '99'

In v4 we end up with '99' as the new local state (relationship.localState = remoteState).

In v5 we end up with '1' as the new local state (relationship.localState = existingState). But in my understanding it should be '99' in the old way.

Notes for the release

[runspired]

This feels like a variant of #9263 and is probably a correct fix