Revert "Time out and dump stacks from R8 processes after 30 minutes"

This reverts commit 29c294b2.

The deadlock in R8 was fixed, and the timeout causes problems when
RBE is enabled and the R8 action gets stuck in a queue for 30
minutes.

Test: checkbuild
Change-Id: Ia0c3826aea3288e9db3bdbd4955e1e16c0a38fe3