Remove deprecated provider, fix flatcar configs, enable CI tests and refactor hetzner terraform (#10002)

* Remove deprecated provider and fix flatcar configs

* Refactor for DRYness

* Add missing line endings

* Enable tests for hetzner terraform in CI

* Add missing inventory for CI tests

contrib/terraform/hetzner/sample-inventory/cluster.tfvars

@@ -0,0 +1,46 @@
+prefix         = "default"
+zone           = "hel1"
+network_zone   = "eu-central"
+inventory_file = "inventory.ini"
+
+ssh_public_keys = [
+  # Put your public SSH key here
+  "ssh-rsa I-did-not-read-the-docs",
+  "ssh-rsa I-did-not-read-the-docs 2",
+]
+
+ssh_private_key_path = "~/.ssh/id_rsa"
+
+machines = {
+  "master-0" : {
+    "node_type" : "master",
+    "size" : "cx21",
+    "image" : "ubuntu-22.04",
+  },
+  "worker-0" : {
+    "node_type" : "worker",
+    "size" : "cx21",
+    "image" : "ubuntu-22.04",
+  },
+  "worker-1" : {
+    "node_type" : "worker",
+    "size" : "cx21",
+    "image" : "ubuntu-22.04",
+  }
+}
+
+nodeport_whitelist = [
+  "0.0.0.0/0"
+]
+
+ingress_whitelist = [
+  "0.0.0.0/0"
+]
+
+ssh_whitelist = [
+  "0.0.0.0/0"
+]
+
+api_server_whitelist = [
+  "0.0.0.0/0"
+]