Don't hardcode path to `ip`.

It's in /usr/sbin/ip on CentOS 7.

PiperOrigin-RevId: 254735519
diff --git a/src/test/shell/integration/linux-sandbox_network_test.sh b/src/test/shell/integration/linux-sandbox_network_test.sh
index 141a473..bb52ab7 100755
--- a/src/test/shell/integration/linux-sandbox_network_test.sh
+++ b/src/test/shell/integration/linux-sandbox_network_test.sh
@@ -42,7 +42,7 @@
 }
 
 function test_network_namespace() {
-  $linux_sandbox $SANDBOX_DEFAULT_OPTS -N  -- /bin/ip link ls &> $TEST_log || fail
+  $linux_sandbox $SANDBOX_DEFAULT_OPTS -N  -- ip link ls &> $TEST_log || fail
   expect_log "LOOPBACK,UP"
 }