repo-install-test: get OBS pub key from proper URL

The public OBS key expired on 2022-05-22 and was replaced with a key
that was only shortly valid until 2022-06-08. Shortly after it was
replaced with a key that is valid longer, until 2024-08-02.

On 2022-06-09, one of the osmocom-repo-install tests started failing.
For some reason, the key in the latest/Debian_10 directory was not
updated to the latest one:
https://download.opensuse.org/repositories/network:/osmocom:/latest/Debian_10/Release.key

Since the key is the same for all of network:osmocom, adjust the
function to download it from a place that the OBS web UI links to when
attempting to download the public GPG key.

I guess the latest/Debian_10/Release.key will get updated once making a
new release and updating the packages in the repository. But sinc
there's a lot of other tasks to do, just use this practical solution for
now.

Change-Id: Idd0fb6e07cba959a36269244b0c7b5c62aaffeee

scripts/repo-install-test/run-inside-docker.sh

@@ -100,7 +100,6 @@ check_env() {
 configure_osmocom_repo_debian() {
 	local proj="$1"
 	local obs_repo="download.opensuse.org/repositories/$(proj_with_slashes "$proj")/$DISTRO_OBSDIR/"
-	local release_key="/var/cache/apt/${proj}_Release.key"
 
 	echo "Configuring Osmocom repository"
 
@@ -108,9 +107,9 @@ configure_osmocom_repo_debian() {
 	if ! [ -e "$release_key" ]; then
 		apt-get update
 		apt install -y wget
-		wget -O "$release_key" "https://$obs_repo/Release.key"
+		wget -O /tmp/Release.key "https://build.opensuse.org/projects/network:osmocom/public_key"
 	fi
-	apt-key add "$release_key"
+	apt-key add /tmp/Release.key
 
 	echo "deb http://$obs_repo ./" > "/etc/apt/sources.list.d/$proj.list"
 	apt-get update