Improvements of builds

Helm Manager Dockerfile now uses "apt get update" in the same command as it installs to avoid intermittent problems.
The Policy Agent pom now has a version for the org.codehaus.mojo:exec-maven-plugin to avoid warning during build.

Issue-ID: NONRTRIC-572
Signed-off-by: elinuxhenrik <henrik.b.andersson@est.tech>
Change-Id: I144b9e3cbbc66673ce4e71973329e08dcb54649b
diff --git a/helm-manager/Dockerfile b/helm-manager/Dockerfile
index cd44c90..96a5831 100644
--- a/helm-manager/Dockerfile
+++ b/helm-manager/Dockerfile
@@ -20,9 +20,8 @@
 ARG JAR
 
 #Install curl
-RUN apt-get update
-RUN apt-get install -y curl
-RUN apt-get install -y wget
+RUN apt-get update && apt-get install -y curl \
+    wget
 
 #Install helm
 RUN wget -O helm.tar.gz https://get.helm.sh/helm-v3.6.1-linux-amd64.tar.gz