Send pcp notification only when the contribution is completed

Send pcp notification only when the contribution is completed

This is a reviewer's cut of https://github.com/civicrm/civicrm-core/pull/19096/
the only substantive difference is the check around the contribution_status_id
in this line https://github.com/civicrm/civicrm-core/pull/19096/files#diff-9f33a2073e9f844dbb842e0737b7df4bce13db31eabe13b9bdd10e1035dbf6d3R612
has had the empty(->contribution_page_id) bit removed - I can
't think why that would be added in & I think it was discussed out but not removed