ci: Add first letter of the K8S_TEST_HOST_TYPE to resource group name

Ideally we'd add the instance_type or the full K8S_TEST_HOST_TYPE but
that exceeds the maximum amount of characteres allowed for the cluster
name.  With this in mind, let's use the first letter of
K8S_TEST_HOST_TYPE instead.

Signed-off-by: Aurélien Bombo <abombo@microsoft.com>
(cherry picked from commit d9ef135)

tests/gha-run-k8s-common.sh

@@ -13,11 +13,25 @@ source "${tests_dir}/common.bash"
 
 K8S_TEST_HOST_TYPE="${K8S_TEST_HOST_TYPE:-small}"
 
+function _print_instance_type() {
+    case ${K8S_TEST_HOST_TYPE} in
+        small)
+            echo "Standard_D2s_v5"
+            ;;
+        normal)
+            echo "Standard_D4s_v5"
+            ;;
+        *)
+            echo "Unknown instance type '${K8S_TEST_HOST_TYPE}'" >&2
+            exit 1
+    esac
+}
+
 function _print_cluster_name() {
     test_type="${1:-k8s}"
 
     short_sha="$(git rev-parse --short=12 HEAD)"
-    echo "${test_type}-${GH_PR_NUMBER}-${short_sha}-${KATA_HYPERVISOR}-${KATA_HOST_OS}-amd64"
+    echo "${test_type}-${GH_PR_NUMBER}-${short_sha}-${KATA_HYPERVISOR}-${KATA_HOST_OS}-amd64-${K8S_TEST_HOST_TYPE:0:1}"
 }
 
 function _print_rg_name() {
@@ -52,21 +66,11 @@ function create_cluster() {
         -l eastus2 \
         -n "${rg}"
 
-    local instance_type=""
-    case ${K8S_TEST_HOST_TYPE} in
-	    small)
-		    instance_type="Standard_D2s_v5"
-		    ;;
-	    normal)
-		    instance_type="Standard_D4s_v5"
-		    ;;
-    esac
-
     az aks create \
         -g "${rg}" \
 	--node-resource-group "node-${rg}" \
         -n "$(_print_cluster_name ${test_type})" \
-        -s "${instance_type}" \
+        -s "$(_print_instance_type)" \
         --node-count 1 \
         --generate-ssh-keys \
         $([ "${KATA_HOST_OS}" = "cbl-mariner" ] && echo "--os-sku AzureLinux --workload-runtime KataMshvVmIsolation")