test-http-bad-server: refactor the writing logic to avoid early return Our ultimate goal is to add another way to define the connection needs to be closed. To do so, we need the "read" code to be more unified. Differential Revision: https://phab.mercurial-scm.org/D12047

test-http-bad-server: replace the default 65537 value in output This is the default block value that we use here and it make the output overall less readable. So we replace it with `~` Differential Revision: https://phab.mercurial-scm.org/D12046

test-http-bad-server: refactor the reading logic to avoid early return Our ultimate goal is to add another way to define the connection needs to be closed. To do so, we need the "read" code to be more unified. Differential Revision: https://phab.mercurial-scm.org/D12045

test-http-bad-server: factor code dealing with "read" in the new object This will make sure both `read` and `readline` do the same processing and make it simpler to update that processing in the future. Differential Revision: https://phab.mercurial-scm.org/D12044

test-http-bad-server: factor code dealing with "write" in the new object This will make sure both `sendall` and `write` do the same processing and make it simpler to update that processing in the future. Differential Revision: https://phab.mercurial-scm.org/D12043

test-http-bad-server: unify log printing for `sendall` and `write` The `write` function was logging before calling the function while the `sendall` function were logging after calling the function. We align the `write` behavior on the `sendall` behavior before unifying the code. Differential Revision: https://phab.mercurial-scm.org/D12042