Put javac, d8 and r8 rules into RBE ninja pool

javac, d8 and r8 rules for module defined in Android.mk files are
running remotely with RBE but are running in the local ninja pool,
restricting them to only running as many jobs in parallel as there
are local CPUs.  Set the ninja pool to let them run 500 jobs in
parallel.

Bug: 228603472
Test: m checkbuild
Change-Id: I60f7859f3657fc1eff0daf0e0a1b0f9fe63551b6