Importing removes other Unity Assets Defining Symbols

[Larzone24]

System Information
Please provide the following information about your system:

• Steam Audio version: 4.4.1
• (If applicable) Unity version: 2021.3.27f1
• (If applicable) Unreal Engine version:
• (If applicable) FMOD Studio version:
• Operating System and version: Windows 10 22H2
• (Optional) CPU architecture (e.g. x86-64, armv7): x64

Issue Description
When importing Steam Audio, the Unity Defining symbols are reset/removed causing issues with other assets. It's not possible to add them back because Steam Audio resets them each time.

Solution: As mentioned in #282 the solution is to not import Assets/Plugins/SteamAudio/Scripts/Editor/Build.cs. The reason I create another issue is that the issue seams to affect more assets then just using Bakery. I am using Bakery as well but this affected most other assets except unity defaults i believe. Also, I didn't get an endless loop.

Steps To Reproduce
Steps to reproduce the behavior:

1. Have a project with already created Unity Defining symbols.
2. Import Steam Audio.
3. After Script reload, check Unity Defining symbols in project settings and many of them are gone.