kernel_install_dep.sh: Use VERSION_ID to differentate between major versions

Now that we're using maching basic images, there is a discrepancy
for rocky 8.6 images:
ROCKY_SUPPORT_PRODUCT='Rocky Linux'.
Since ROCKY_SUPPORT_PRODUCT is not the same for all versions, use VERSION_ID
instead.

Signed-off-by: Roxana Nicolescu <rnicolescu@ciq.com>

Author: roxanan1996

kernel_install_dep.sh

@@ -210,14 +210,14 @@ install_kselftest_deps_10() {
     wheel
 }
 
-case "$ROCKY_SUPPORT_PRODUCT" in
-    Rocky-Linux-10)
+case "${VERSION_ID%%.*}" in
+    10)
         install_kselftest_deps_10
         ;;
-    Rocky-Linux-9)
+    9)
         install_kselftest_deps_9
         ;;
-    Rocky-Linux-8)
+    8)
         install_kselftest_deps_8
         ;;
 esac