[Sanitizer][RISCV][AArch64][Android] Adjust allocator tests

On 64-bit systems with small VMAs (e.g. 39-bit) we can't use
SizeClassAllocator64 parameterized with size class maps containing a large
number of classes, as that will make the allocator region size too small
(< 2^32). Several tests were already disabled for Android because of this.

This patch provides the correct allocator configuration for RISC-V
(riscv64), generalizes the gating condition for tests that can't be enabled
for small VMA systems, and tweaks the tests that can be made compatible with
those systems to enable them.

I think the previous gating on Android should instead be AArch64+Android, so
the patch reflects that.

Differential Revision: https://reviews.llvm.org/D97234