OpenSUSE 15.5: set working mirrors for zypper

OpenSUSE 15.5 provision can fail to a failed zypper install with
qemu-guest-agent due to a broken/expired mirror. This may be
eventually fixed by the package manager. This changes adds a working
source for zypper and the package.

Sometimes installing any package with zypper can output:
"Repository 'Update repository of openSUSE Backports' is invalid.".
This may mean a current mirror/repo for it is not functioning at that time. Specifying a functioning mirror fixes this.

Change-Id: I7b8ea8f1db291a1001a7d062a3da91ded99301f2
Reviewed-by: Simo Fält <simo.falt@qt.io>

coin/provisioning/qtci-linux-openSUSE-15.5-x86_64/04-zypperpackages.sh

@@ -3,6 +3,12 @@
 
 set -ex
 
+sudo zypper clean
+sudo rm -rf /var/cache/zypp
+sudo zypper rr repo-backports-update
+sudo zypper ar -f http://ftp.funet.fi/pub/mirrors/ftp.opensuse.com/pub/opensuse/update/leap/15.5/backports/ repo-backports-update
+sudo zypper refresh
+
 sudo zypper -nq install git gcc9 gcc9-c++ ninja
 sudo /usr/sbin/update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 1 \
                                      --slave /usr/bin/g++ g++ /usr/bin/g++-9 \

coin/provisioning/qtci-linux-openSUSE-15.5-x86_64/70-install_QemuGA.sh

@@ -5,5 +5,6 @@
 # This script installs QEMU Guest Agent
 
 set -ex
-
+sudo zypper addrepo --no-gpgcheck https://download.opensuse.org/repositories/Virtualization/15.5/Virtualization.repo
+sudo zypper ref -f
 sudo zypper -nq install qemu-guest-agent