Fix interaction between url-handler-mode and browse-url

* lisp/net/browse-url.el (browse-url): Don't expand any URLs (like
"man:") that have a scheme when using `url-handler-mode' (bug#37056).
1 job for master in 90 minutes and 1 second (queued for 3 seconds)
Status Job ID Name Coverage
failed #3088


Name Stage Failure
test-all Test The script exceeded the maximum execution time set for the job
  GEN      lisp/calendar/iso8601-tests.log
ELC lisp/calendar/parse-time-tests.elc
GEN lisp/calendar/parse-time-tests.log
ELC lisp/calendar/time-date-tests.elc
GEN lisp/calendar/time-date-tests.log
ELC lisp/calendar/todo-mode-tests.elc
GEN lisp/calendar/todo-mode-tests.log
Pulling docker image gitlab/gitlab-runner-helper:x86_64-d0b76032 ...
ERROR: Job failed: execution took longer than 1h30m0s seconds