Fix Jenkins PR build by adding "apt-get update" to jenkins_packages.sh

[iguessthislldo]

Try to fix PR jenkins when running jenkins_packages.sh by adding a apt-get update.

E: Failed to fetch http://security.debian.org/debian-security/pool/updates/main/g/ghostscript/libgs9-common_9.25~dfsg-0+deb9u1_all.deb 404 Not Found [IP: 151.101.44.204 80]
E: Failed to fetch http://security.debian.org/debian-security/pool/updates/main/g/ghostscript/libgs9_9.25~dfsg-0+deb9u1_amd64.deb 404 Not Found [IP: 151.101.44.204 80]
E: Aborting install.

Also fail script automatically by adding set -e.

[iguessthislldo]

@mitza-oci Looks like Azure is having some kind of internal error, but apt-get update fixed the jenkins build.