tests: Fix for running in RHEL

* Generalize setting of $TEST_OS
 * chromium-headless is not in RHEL 8, install it from EPEL.

tests/browser.sh

@@ -41,7 +41,22 @@ make bots test/common
 # only install a subset to save time/space
 npm install chrome-remote-interface sizzle
 
-export TEST_OS=fedora-32
+. /etc/os-release
+export TEST_OS="${ID}-${VERSION_ID/./-}"
+# HACK: upstream tests don't recognize rhel-8-3 yet
+if [ "$TEST_OS" = "rhel-8-3" ]; then
+    export TEST_OS=rhel-8-2
+fi
+
+# install browser; on RHEL, use chromium from epel
+if ! rpm -q chromium-headless; then
+    if [ "$ID" = "rhel" ]; then
+        dnf install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
+        dnf config-manager --enable epel
+    fi
+    dnf install -y chromium-headless
+fi
+
 export TEST_AUDIT_NO_SELINUX=1
 
 # run tests

tests/tests.yml

@@ -11,7 +11,6 @@
     required_packages:
     - cockpit-podman
     - cockpit-ws
-    - chromium-headless
     - git
     - libvirt-python3
     - make