Set default pool when RBE or goma is enabled

Pass --default_pool=local_pool to kati when RBE or goma is enabled
to put most rules into the local_pool.  Specific rules that support
RBE or goma will set .KATI_NINJA_POOL := none to remove themselves
from the local_pool.  Passing --default_pool will also disable the
hack in kati that sets the pool based on the presence of the string
"/gomacc" in the command line.

Fixes: 143938974
Test: inspect pools in build-${TARGET-PRODUCT}.ninja for m USE_RBE=true
Test: inspect pools in build-${TARGET-PRODUCT}.ninja for m USE_GOMA=true
Change-Id: I839b2488383fcd63fffd613e25b0b9abcb72b567

ui/build/ninja.go

@@ -43,7 +43,7 @@ func runNinja(ctx Context, config Config) {
 	args = append(args, config.NinjaArgs()...)
 
 	var parallel int
-	if config.UseGoma() || config.UseRBE() {
+	if config.UseRemoteBuild() {
 		parallel = config.RemoteParallel()
 	} else {
 		parallel = config.Parallel()