scripts: replace /bin/bash by /usr/bin/env bash

Test Plan: Set up environment locally; CI

X-Origin-Diff: phab/D759
GitOrigin-RevId: 01142b03dcfb44c1dcb42169cc9af187c1518107
diff --git a/scripts/create_container.sh b/scripts/create_container.sh
index c6d77a6..2c60e5d 100755
--- a/scripts/create_container.sh
+++ b/scripts/create_container.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -euo pipefail
 
 # Our local user needs write access to /dev/kvm (best accomplished by