Merge pull request #19014 from eileenmcnaughton/cancel

dev/core#927 Add test demonstrating that an extraneous activity is being created & fix

diff --cc CRM/Contribute/BAO/Contribution.php
Simple merge

diff --cc ext/contributioncancelactions/contributioncancelactions.php
Simple merge

diff --cc tests/phpunit/CRM/Member/Form/MembershipTest.php
Simple merge