Output *TS testcases to common testcase folders.

Aggregates the different *TS testcases into two common folders,
one under each the host and product hierarchies.

Bug: 34715822
Test: `make cts -j` and checked the contents of both:
out/host/linux-x86/testcases/ &
out/host/linux-x86/cts/android-cts/testcases/

Change-Id: I7d5201998ddcb011ecc687c272a0d0a36da248b7