[FIX] config: empty argument --foo= to disable

In the odoorc file, set a `logfile` path, but disable it via the command
line with `--logfile=`. The logs are output to the logfile configured in
the config file instead of stdout.

Parsing `--logile=` yield an empty string which was interpreted as
argument not set and skipped.

Closes #3852

closes odoo/odoo#60990

X-original-commit: bae0d99b
Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>
Signed-off-by: Julien Castiaux <Julien00859@users.noreply.github.com>