Merge pull request #68614 from tchaikov/wip-test-osd-fix-leaks

test/osd: fix Message and Connection refcount leaks

Reviewed-by: Alex Ainscow <aainscow@uk.ibm.com>

diff --cc src/test/osd/ECPeeringTestFixture.cc
Simple merge

diff --cc src/test/osd/MockPGBackendListener.h
Simple merge

diff --cc src/test/osd/PGBackendTestFixture.cc
Simple merge