[Embeddable Rebuild] Keep panel title in sync with saved object title

[Heenawter]

Describe the bug:
With React embeddables, we are always serializing the panel title even if it is equal to the default panel title / saved object title.

Steps to reproduce:

1. Add a by-reference Map embeddable to your dashboard - keep the default panel title.
2. Edit that Map saved object's title
3. Go back to the dashboard
4. The Map panel still shows the original title and not the updated one 🔥

Expected behavior:
When the panel title is not overwritten and it is equal to the default panel title, it should not be serialized.

Screenshots (if relevant):

Screen.Recording.2024-07-22.at.9.23.31.AM.mov

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)