stream-clone-test: simplify the test for getbundle with stream=1
The core of this tests is about checking we receive a stream bundle with such
request. We don't need to look at too much of the details of the stream itself.
Since the content of the stream if shifting overtime, Such check is very
fragile and consume a lot of time for little value when adjusting formats,
caches, and protocol.
So we reduce the size of what we check to focus on "is this a stream clone"
question.
#require docutils gettext
$ $TESTDIR/check-gendoc el
checking for parse errors