Stop using _source.mode attribute in traces-otel builtin template (elastic#117487) (elastic#117492)

The traces-otel@mappings component template is configured to use logsdb. No need to configure source mode separately.

Author: martijnvg

x-pack/plugin/otel-data/src/main/resources/component-templates/[email protected]

@@ -10,8 +10,6 @@ template:
       sort:
         field: [ "resource.attributes.host.name", "@timestamp" ]
   mappings:
-    _source:
-      mode: synthetic
     properties:
       trace_id:
         type: keyword

x-pack/plugin/otel-data/src/main/resources/resources.yaml

@@ -1,7 +1,7 @@
 # "version" holds the version of the templates and ingest pipelines installed
 # by xpack-plugin otel-data. This must be increased whenever an existing template is
 # changed, in order for it to be updated on Elasticsearch upgrade.
-version: 6
+version: 7
 
 component-templates:
   - otel@mappings