Dockerfile-dev: fix image build for centos:8

Fixes applied:
* there is no openssh-client package, there is openssh-clients
* removed misplaced '&&' in yum install command

Change-Id: I0b1aec97acfaba034899373fc80cbfbbce265c65
diff --git a/centos/8/Dockerfile-dev b/centos/8/Dockerfile-dev
index 09ba812..d4ec95d 100644
--- a/centos/8/Dockerfile-dev
+++ b/centos/8/Dockerfile-dev
@@ -6,10 +6,10 @@
 # Allow remote connectivity and sudo and install OpenJDK and Git
 # (pre-trans Gerrit script needs to have access to the Java command)
 RUN yum -y install \
-    openssh-client \
+    openssh-clients \
     initscripts \
     sudo \
-    java-11-openjdk && \
+    java-11-openjdk \
     git && \
     yum -y clean all