chore: enable code insights in sg start enterprise (#55172)

This was excluded for historical reasons that no longer apply. This will
reduce confusion when people try to start code insights locally.

## Test plan

Code Insights starts with `sg start enterprise`

<!-- All pull requests REQUIRE a test plan:
https://docs.sourcegraph.com/dev/background-information/testing_principles
-->

sg.config.yaml

@@ -1024,6 +1024,9 @@ commandsets:
       - zoekt-web-1
       - blobstore
       - embeddings
+    env:
+      DISABLE_CODE_INSIGHTS_HISTORICAL: false
+      DISABLE_CODE_INSIGHTS: false
 
   enterprise-e2e:
     <<: *enterprise_set