boost: move without-python option into bootstrap stage.

Specifying 'without-python' option for ./b2 takes precedence over all
'without-libraries' options specified previously for ./boostrap.sh

Closes #22988.

Signed-off-by: Andrei Polushin <polushin@gmail.com>
Closes #22988.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>