tests: fix http-bad-server expected errors for python 3.10 (issue6643) The format of the error message changed with this version of Python. This also removes obsolete Python 3 checks.

status: let `--no-copies` override `ui.statuscopies`

run-tests: display the time it took to install Mercurial It will help make people aware of this critical step and to assess the time it takes in various options (like a CI run for example).