tests: Replace $stream with 9-stream

Lorax doesn't use the variable substitution from the host so hard-code
this in the repo files before passing them to lorax.

Related: RHEL-28654

tests/scripts/run_tests.sh

@@ -13,6 +13,10 @@ if [ -z "$REPOS" ]; then
     exit 1
 fi
 
+# The c9s tmt systems have started using $stream in the repo urls as of 6/2024, substitute
+# 9-stream for this variable so that they can be passed to lorax
+sed -i 's/$stream/9-stream/g' /etc/yum.repos.d/*.repo
+
 # Run lorax using the host's repository configuration file
 lorax --product="Red Hat Enterprise Linux" --version=9 --release=9 --volid="RHEL-9-test" \
       $REPOS --isfinal --nomacboot /var/tmp/lorax-rhel9-iso/