[MISC] Remove format.sh (#28906)

Signed-off-by: Kuntai Du <kuntai@uchicago.edu>

format.sh

@@ -1,6 +0,0 @@
-#!/bin/bash
-
-echo "vLLM linting system has been moved from format.sh to pre-commit hooks."
-echo "Please run 'pip install -r requirements/lint.txt', followed by"
-echo "'pre-commit install' to install the pre-commit hooks."
-echo "Then linters will run automatically before each commit."