Tests: Refixed the put_alias tests

The missing/null index parameter is in the URL, not the body.
So it should be required, and throw a param error if not provided.

Relates #7863

rest-api-spec/api/indices.put_alias.json

@@ -8,6 +8,7 @@
       "parts": {
         "index": {
           "type" : "list",
+          "required" : true,
           "description" : "A comma-separated list of index names the alias should point to (supports wildcards); use `_all` to perform the operation on all indices."
         },
         "name": {

rest-api-spec/test/indices.put_alias/all_path_options.yaml

@@ -106,7 +106,7 @@ setup:
 
 
   - do:
-      catch: request
+      catch: param
       indices.put_alias:
         name: alias
 
@@ -116,6 +116,6 @@ setup:
 
 
   - do:
-      catch: request
+      catch: param
       indices.put_alias: {}