reset: remove 'reset.quiet' config option

reset: remove 'reset.quiet' config option

Remove the 'reset.quiet' config option, remove '--no-quiet' documentation in
'Documentation/git-reset.txt'. In 4c3abd0551 (reset: add new reset.quiet
config setting, 2018-10-23), 'reset.quiet' was introduced as a way to
globally change the default behavior of 'git reset --mixed' to skip index
refresh.

However, now that '--quiet' does not affect index refresh, 'reset.quiet'
would only serve to globally silence logging. This was not the original
intention of the config setting, and there's no precedent for such a setting
in other commands with a '--quiet' option, so it appears to be obsolete.

In addition to the options & its documentation, remove 'reset.quiet' from
the recommended config for 'scalar'.

Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>