Add wait timeout to docker exec measurement job

Some commands in dev where timing out, perhaps due to runner contraints
(the docker runner in dev was meant for building docker images, not for running
the gitlab docker image)

lib/gitlab/docker_image_memory_measurer.rb

@@ -157,11 +157,11 @@ module Gitlab
       [pid_command_hash_array, smem_result_hash_array]
     end
-    def container_exec_command(container, command, log_file)
+    def container_exec_command(container, command, log_file, timeout = 120)
       # make sure the folder exists
       FileUtils.mkdir_p debug_output_dir unless debug_output_dir.nil?
-      stdout, stderr, code = container.exec(command)
+      stdout, stderr, code = container.exec(command, wait: timeout)
       stdout = stdout.join('')
       stderr = stderr.join('')