Bug Report - Animation Editor opens with Blank "Default" motion set when opening an anim graph from Inspector.

[GaianHelmers]

Describe the bug
When opening an anim graph from the [Open in Animation Editor] button in inspector, the Animation Editor always starts with a blank "default" as the first motion set, with the default from the anim graph as a second "default" motion set.

This prevents all the animations in the graph from being previewed until you delete the blank default motion set, to cause the loaded default to take precedence.

Assets required
A character model with an animation graph that uses a moveset named default.

Steps to reproduce
Steps to reproduce the behavior:

1. Select your animated character.
2. Edit the "Anim Graph" component by clicking the [Open in Animation Editor] button beside your target anim graph file.
3. Navigate to the Motions tab.
4. See two default motion sets. The first one blank, the second one with your default motions.
5. With both defaults present, try running the graph animation preview. It should not animate.
6. Delete the blank default move sets, follow the prompts, then try to run the animations again. It works now.

Expected behavior
The loaded anim graph would carry all it's settings over for editing in the animation editor.

Actual behavior
Blank default settings remain and unique settings from the anim graph get added secondarily. Preventing the system from connecting the motions to the anim graph.

Screenshots/Video
https://github.com/o3de/o3de/assets/55327922/f9342eeb-e0d0-4be4-af3f-956ea3388061

Found in Branch
Dev - 9292148
But it's been around for a long time.

Desktop/Device (please complete the following information):

• Device: Desktop
• OS: Windows 10
• CPU Intel(R) Core(TM) i7-10700K CPU @ 3.80GHz 3.79 GHz
• GPU MSI 3070
• Memory 64GB