ci : gracefully shut down the server (#21110)

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

tools/server/tests/utils.py

@@ -288,7 +288,15 @@ class ServerProcess:
             server_instances.remove(self)
         if self.process:
             print(f"Stopping server with pid={self.process.pid}")
-            self.process.kill()
+            self.process.terminate()
+            try:
+                self.process.wait(timeout=5)
+            except subprocess.TimeoutExpired:
+                print(f"Server pid={self.process.pid} did not terminate in time, killing")
+                self.process.kill()
+                self.process.wait(timeout=5)
+            except Exception as e:
+                print(f"Error waiting for server: {e}")
             self.process = None
 
     def make_request(