Remove invalid tools list from whats-new-from-release-notes agent (#36984)

* Initial plan

* Plan: remove invalid tools list from agent frontmatter

Agent-Logs-Url: https://github.com/dotnet/AspNetCore.Docs/sessions/3e0ae18e-31ba-4964-875e-cc73813abad8

Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wadepickett <10985336+wadepickett@users.noreply.github.com>

Author: Copilot

.github/agents/whats-new-from-release-notes.agent.md

@@ -7,10 +7,6 @@ description: >
   Use this agent when processing new .NET preview release notes into the
   What's New article, or when checking for incremental updates to
   already-processed release notes.
-tools:
-  - githubread
-  - lexical-code-search
-  - semantic-code-search
 ai-usage: ai-assisted
 author: tdykstra
 ms.author: wpickett