Apache HTTP: run more tests

Apache HTTP: run more tests

Factor out the test parameterization to use both connection factories
into a common super class and use it in more tests.

This made HttpClientTests.testV2HttpSubsequentResponse() fail for
Apache HTTP. The test used the pattern

  - create POST connection
  - setDoOutput(true)
  - connect()
  - write output stream
  - get & read input stream

This pattern is never used in JGit, which actually calls connect() only
in one case in LFS, and that's on a HEAD request.

The above pattern works on JDK, but fails on Apache HTTP because with
Apache HTTP a connect() actually executes the full request including
writing the entity. To work with Apache HTTP, the pattern would need
to be

  - create POST connection
  - setDoOutput(true)
  - write output stream
  - connect()
  - get & read input stream

which is fine for both. JDK connects implicitly in getOutputStream()
and treats the later explicit connect() as a no-op, and Apache works
because the entity is written when connect() is called.

Because JDK connects implicitly on getOutputStream(), the following
pattern also works with JDK:

  - create POST connection
  - setDoOutput(true)
  - write output stream
  - get & read input stream

Support this with Apache HTTP too: let getInputStream() execute
the request if it wasn't executed already.

Remove explicit connect() calls from test code, since JGit doesn't do
those either.

Change-Id: Ica038c00a7b8edcc01d5660d18e961146305b87f
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>