Another attempt to fix vpython in Cloud Build.

I think the underlying issue is switching to the 'skia' user
to do the build. Instead let's try building as root and then
chown the generated files which are then used by subsequent
Dockerfiles.

Bug:993053
Change-Id: I314a6c83f70e611ec0fafe93ae136d218d153cfb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/247107
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Joe Gregorio <jcgregorio@google.com>
diff --git a/docker/skia-release/Dockerfile b/docker/skia-release/Dockerfile
index 952e959..d8670b4 100644
--- a/docker/skia-release/Dockerfile
+++ b/docker/skia-release/Dockerfile
@@ -11,8 +11,6 @@
   && groupadd -g 2000 skia \
   && useradd -u 2000 -g 2000 --home-dir /workspace/__cache skia
 
-USER skia
-
 ADD --chown=skia:skia https://storage.googleapis.com/swiftshader-binaries/OpenGL_ES/Latest/Linux/libGLESv2.so /usr/local/lib/libGLESv2.so
 ADD --chown=skia:skia  https://storage.googleapis.com/swiftshader-binaries/OpenGL_ES/Latest/Linux/libEGL.so /usr/local/lib/libEGL.so
 RUN cd /tmp \
@@ -46,7 +44,8 @@
   && ./bin/fetch-gn \
   && ./bin/gn gen out/Static \
   && git rev-parse HEAD > VERSION \
-  && /tmp/depot_tools/ninja -C out/Static
+  && /tmp/depot_tools/ninja -C out/Static \
+  && chown -R skia:skia out/Static
 
 # Uncomment the lines below and update the ref to patch in a CL.
 #