[Refactor] Remove unused dead code (#33718)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

vllm/collect_env.py

@@ -146,14 +146,6 @@ def run_and_parse_first_match(run_lambda, command, regex):
     return match.group(1)
 
 
-def run_and_return_first_line(run_lambda, command):
-    """Run command using run_lambda and returns first line if output is not empty."""
-    rc, out, _ = run_lambda(command)
-    if rc != 0:
-        return None
-    return out.split("\n")[0]
-
-
 def get_conda_packages(run_lambda, patterns=None):
     if patterns is None:
         patterns = DEFAULT_CONDA_PATTERNS