Blender Git Loki

XR: Improve "Invalid stage ref space" warning

Originally mentioned that absolute tracking was disabled, which is
wrong because absolute tracking (skipping application of eye offsets)
is always available, although it may not give the expected result of
persistent tracking origins across sessions if the stage space is
unavailable (hence the need for a warning).

Now, the warning makes no mention of absolute tracking, instead
informing the user that the local space fallback will be used and
that they should define tracking bounds via the XR runtime if they
wish to use the stage space.