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
diff --git a/ui/build/kati.go b/ui/build/kati.go
index a7799ea..307475a 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -89,6 +89,10 @@
 		args = append(args, "--empty_ninja_file")
 	}
 
+	if config.UseRemoteBuild() {
+		args = append(args, "--default_pool=local_pool")
+	}
+
 	cmd := Command(ctx, config, "ckati", executable, args...)
 	cmd.Sandbox = katiSandbox
 	pipe, err := cmd.StdoutPipe()