Remove references to modern_python_path_defaults

The new python path behavior has been enabled by default,
so enabling it manually with modern_python_path_defaults
is no longer necessary.

Bug: 245583294
Test: Presubmits
(cherry picked from https://android-review.googlesource.com/q/commit:ab45e01a0dd19c0e9cce82d1b94cd39a5c1ec0a0)
Merged-In: I0d2a15216be9481f3851a054351c20fbbbde8b5f
Change-Id: I0d2a15216be9481f3851a054351c20fbbbde8b5f