prometheus: simplify runtime test

Passed argument no longer contains the release.

Signed-off-by: Paul Spooren <mail@aparcar.org>

utils/prometheus/test.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
 
-prometheus --version 2>&1 | grep "${2%%-*}"
+prometheus --version 2>&1 | grep "$2"