Improve build image time

Signed-off-by: Vasyl Razinkov <vasyl.razinkov@est.tech>
Change-Id: I325b2ba1626effee614e5e82aead4a01adb13c5d
Issue-ID: SDC-4526
diff --git a/asdctool/sdc-cassandra-init/Dockerfile b/asdctool/sdc-cassandra-init/Dockerfile
index 82ac337..4116509 100644
--- a/asdctool/sdc-cassandra-init/Dockerfile
+++ b/asdctool/sdc-cassandra-init/Dockerfile
@@ -24,11 +24,7 @@
     ruby-dev \
     libffi-dev \
     libxml2-dev && \
-    gem install public_suffix -v 4.0.7 --no-document && \
-    gem install multipart-post -v 2.2.0 --no-document && \
-    gem install etc -v 1.3.0 --no-document && \
-    gem install bundler -v 2.3.26 --no-document && \
-    gem install chef:13.8.5 berkshelf:6.3.1 io-console:0.4.6 webrick --no-document && \
+    gem install --no-update-sources public_suffix:4.0.7 multipart-post:2.2.0 etc:1.3.0 bundler:2.3.26 chef:13.8.5 berkshelf:6.3.1 io-console:0.4.6 webrick --no-document && \
     apt-get update -y && apt-get remove bash -y --allow-remove-essential && \
     apt-get install -y binutils && apt-get clean && gem cleanup