controller/sysroot: Skip setup board in InstallPackages

Skip setup_board in build_packages for builders. Allows configuring
the sysroot only in Sysroot/Create, and eventually simplifying the
InstallPackages request.

BUG=chromium:945003
TEST=cq

Change-Id: I55e18a64ccc3eb938526248fa6320475a283a312
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2774608
Tested-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Michael Mortensen <mmortensen@google.com>
Reviewed-by: Michael Mortensen <mmortensen@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/api/controller/sysroot.py b/api/controller/sysroot.py
index 48b8d16..59b9ef7 100644
--- a/api/controller/sysroot.py
+++ b/api/controller/sysroot.py
@@ -186,7 +186,8 @@
       package_indexes=package_indexes,
       use_flags=use_flags,
       use_goma=use_goma,
-      incremental_build=False)
+      incremental_build=False,
+      setup_board=False)
 
   try:
     sysroot.BuildPackages(build_target, target_sysroot, build_packages_config)