fix: remove watch path that's gone (#63746)

https://github.com/sourcegraph/sourcegraph/pull/63736 removed rockskip
files, which lead to `sg start` failing because it was still watching
those. This PR removes the watch and lets `sg start` succeed again.

## Test plan

Existing CI, manual test of `sg start`

## Changelog

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sg.config.yaml

@@ -255,7 +255,6 @@ commands:
       - lib
       - internal
       - cmd/symbols
-      - internal/rockskip
 
   embeddings:
     cmd: |