Always build mk2rbc/rbcrun

Currently, mk2rbc/rbcrun aren't built in certain phases
of the build, which causes the Starlark product configuration
to fail when using get_build_var if a regular build hasn't
been run before.

Bug: 226677850
Test: Manually
Change-Id: If85608eef63be25fddc4d916c82247c13eb0195f
diff --git a/scripts/rbc-run b/scripts/rbc-run
index b8a6c0c..8d93f0e 100755
--- a/scripts/rbc-run
+++ b/scripts/rbc-run
@@ -6,8 +6,8 @@
 set -eu
 
 declare -r output_root="${OUT_DIR:-out}"
-declare -r runner="${output_root}/soong/rbcrun"
-declare -r converter="${output_root}/soong/mk2rbc"
+declare -r runner="${output_root}/rbcrun"
+declare -r converter="${output_root}/mk2rbc"
 declare -r launcher="${output_root}/rbc/launcher.rbc"
 declare -r makefile_list="${output_root}/.module_paths/configuration.list"
 declare -r makefile="$1"