TSDB: Fix template name in test

We had a test that was periodically failing with a bad expected warning.
It turns out I had written the wrong template name in the warning and
the test didn't fail on the PR due to bad luck.

Closes #78726

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/data_stream/150_tsdb.yml

@@ -6,7 +6,7 @@ setup:
 
   - do:
       allowed_warnings:
-        - "index template [tsdbds-template1] has index patterns [simple-data-stream1] matching patterns from existing older templates [global] with patterns (global => [*]); this template [my-template1] will take precedence during new index creation"
+        - "index template [my-template1] has index patterns [k8s*] matching patterns from existing older templates [global] with patterns (global => [*]); this template [my-template1] will take precedence during new index creation"
       indices.put_index_template:
         name: my-template1
         body: