Use a more portable path for Android to write temp files to.

/sdcard is *not* guaranteed to be available, but /data/local/tmp is.

In some emulated situations, /sdcard may not be mounted, may not be R/W, or
mounting may be delayed until *after* the test process begins.

This is fairly common location to use. See e.g.:
https://reviews.llvm.org/D9569

PiperOrigin-RevId: 270909282