common: do not dup the options when reexpanding

common: do not dup the options when reexpanding

The old code will store all the options, which has `$pid` in them,
in may_reexpand_meta map. And when reexpanding later, the reexpand
code will dup them with a higher priority(CONF_OVERRIDE).

This will be a problem, if the default value has `$pid` and be
stored in the may_reexpand_meta map, and then the code set a new
different value, which may have no `$pid`, from CLI or config file.
The reexpand will override it with the default value always.

This will do not duplicate the options with CONF_OVERRIDE priority
when reexpanding, just refresh them and call the observers. And the
finalize_reexpand_meta() will always be called after the fork() is
done in child processes.

Fixes: https://tracker.ceph.com/issues/48240
Signed-off-by: Xiubo Li <xiubli@redhat.com>