Increase the timeout value of Libcore tests for gcstress non-debug configs.

Increase the per-test timeout value passed to Vogar by script
`tools/run-libcore-tests.sh` for gcstress non-debug configurations
from 900 seconds (15 minutes) to 1200 seconds (20 minutes), to allow
long Libcore tests (like `libcore.java.lang`) to finish on slower
devices like bonito (Pixel 3a XL).

Test: Rely on the ART Buildbot (LUCI)
Bug: 158195843
Change-Id: I9353d8a072ddfcbdb01cb4eba228fbcdd01596ee
1 file changed