remove unused internal tool (#5645)

closes: DASH-556

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## PR-Codex overview
This PR focuses on removing files related to RPC validation within the dashboard application, indicating a potential refactor or removal of unnecessary functionality.

### Detailed summary
- Deleted the file `apps/dashboard/src/hooks/chains/useRpcValidation.ts`
- Removed the file `apps/dashboard/src/app/(dashboard)/chain/validate/page.tsx`
- Eliminated the file `apps/dashboard/src/app/(dashboard)/chain/validate/ChainValidation.tsx`

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Author: jnsdls