stream-clone: split the stream part out of test-persistent-nodemap.t
We want to test multiple variants, so let's make it an independent test.
Small adaptations and simplifications are needed in the test output as the
tested repository is now shorter.
https://bz.mercurial-scm.org/1089
$ hg init repo
$ cd repo
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..