Enable PartitionAlloc by default

The previous issue on Android has been identified. It was caused by
Qualcomm's proprietary gralloc module /ventor/lib64/libgralloccore.so
that managed to bypass partition_alloc for malloc, but not for free.

This is known to be possible on Android, so we just enable the fallback
to allow the test to pass.

Bug: 351867706
Change-Id: I46ed9443a76ae25847ed7256db3dbe764cab354d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1202397
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>