slapos.cookbook: don't use 'sh -e' shebang in createWrapper

This partially reverts f834a06.

This shebang was causing issues with testnodes. See
https://lab.nexedi.com/nexedi/slapos/-/commit/f834a06f32588f899dc4235c245db5c6ae3f659a#note_228158

Author: Tomo59

slapos/recipe/librecipe/generic.py

@@ -169,7 +169,7 @@ def createWrapper(self, path, args, env=None, sig_ign=None, **kw):
     # here (note that this can't be done correctly with a POSIX shell, because
     # the process can't be given a name).
 
-    lines = ['#!/bin/sh -e']
+    lines = ['#!/bin/sh']
 
     if sig_ign:
       lines.append("trap '' " + sig_ign)