Fixing ingest simulate yaml rest test when there is a global legacy template (#115559) (#115599)

The ingest simulate yaml rest test `Test mapping addition works with
indices without templates` tests what happens when an index has a
mapping but matches no template at all. However, randomly and rarely a
global match-all legacy template is applied to the cluster. When this
happens, the assumptions for the test fail since the index matches a
template. This PR removes that global legacy template so that the test
works as intended. Closes #115412 Closes #115472

Author: masseyke

qa/smoke-test-ingest-with-all-dependencies/src/yamlRestTest/resources/rest-api-spec/test/ingest/80_ingest_simulate.yml

@@ -1588,6 +1588,13 @@ setup:
       cluster_features: ["simulate.support.non.template.mapping"]
       reason: "ingest simulate support for indices with mappings that didn't come from templates added in 8.17"
 
+  # A global match-everything legacy template is added to the cluster sometimes (rarely). We have to get rid of this template if it exists
+  # because this test is making sure we get correct behavior when an index matches *no* template:
+  - do:
+      indices.delete_template:
+        name:   '*'
+        ignore: 404
+
   # First, make sure that validation fails before we create the index (since we are only defining to bar field but trying to index a value
   # for foo.
   - do: