test: ceph_test_rados_api_io_pp coverage for zero+truncate requests

Improve test coverage for requests that combine zero + truncate operations,
also add tests for truncate + truncate operations and truncates to
non-existent objects which test related code paths.

Add tests for Replica, Classic EC and Fast EC.

Signed-off-by: Bill Scales <bill_scales@uk.ibm.com>