[FMOD/Core] Sound comes from left side when listener and source are roughly at the same position

[Schroedingers-Cat]

System Information
Please provide the following information about your system:

• Steam Audio version: 4.8.1
• FMOD Studio version: 2.2.20
• Operating System and version: Linux, macOS, Windows
• CPU architecture (e.g. x86-64, armv7): x64, ARM64

Issue Description
When the listener is very close to or exactly at the source, the source will be spatialized 90° to the left.
While listener at source position is a special case for a math function extracting a direction, it should nevertheless be as neutral as possible. Left isn't a neutral option because it is also absence on the right side. A much more neutral option would be the front since it gives both sides equal weight.

Interestingly, FMOD Studio seems to do this by default - but only after the first playback of an event's lifetime. So the first time after loading an event, it plays back fully left (but due to #556 this can be a bit less prominent when not listening very closely). After that, FMOD slightly nudges the source away from the listener, a tiny bit to its front.

Steps To Reproduce
Steps to reproduce the behavior:

1. Open an event with a clear transient material that makes use of the Steam Audio Spatializer
2. Start playback and watch the channel level meters or listen carefully
3. You should see/hear the sound coming from the left side (or without a fix for [FMOD/Core] Spatializer smooths panning after idle #556 moving to the left side) (bug)
4. Stop playback - note how FMOD now nudges the source position indicator slightly above the listener position
5. Start playback again
6. You should see/hear the sound coming from the center (expected) (or without a fix for [FMOD/Core] Spatializer smooths panning after idle #556 moving from the left to the center)

SteamAudio-SoundFromLeftWhenListenerIsAtSource.mp4