rm get_pr_comments tool

authenticating the tool is hairy in sdk + GH actions container env, and its been broken for more than a month and no one has known. ripping it out

Author: sayansisodiya

README.md

@@ -207,8 +207,7 @@ The app uses Amp's toolbox feature to provide GitHub operations as simple execut
 
 Available tools:
 - `leave_inline_comment` - Leave line-specific code feedback
-- `leave_general_comment` - Leave overall PR feedback  
-- `get_pr_comments` - Retrieve existing PR comments
+- `leave_general_comment` - Leave overall PR feedback
 
 ## Architecture
 

config.yml

@@ -49,8 +49,6 @@ amp:
 
     IMPORTANT: Always use the tools available in the toolbox (prefixed with tb__) to leave comments while performing your review.
 
-    Read any existing PR comments before leaving new comments. 
-
     Review the diff content to identify issues. If you find any issues, leave specific inline comments for each issue found.
 
     Suggested fixes are optional snippets of code that can directly replace the full line the indicated issue is on for an inline comment.