transport: respect verbosity when setting upstream

transport: respect verbosity when setting upstream

A command such as `git push -qu origin feature` will print "Branch
'feature' set up to track remote branch 'feature' from 'origin'." even
when --quiet is passed. In this case it's because install_branch_config() is
always called with BRANCH_CONFIG_VERBOSE.

struct transport keeps track of the desired verbosity. Fix the above
issue by passing BRANCH_CONFIG_VERBOSE conditionally based on that.

Signed-off-by: Øystein Walle <oystwa@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>