We can not rely on the db engine returning results in the same order
if no order is specified in get_comments and get_annotations.
Also fixing a related unit test.
Get rid of the gc_collect_cycles() that only was
hiding incorrectly left open files. This must be fixed
in code when possible. And pdf libs allow us to do so.
Note that a lot of gc_collect_cycles() were added
in MDL-47675, I'd recommend to take a look to all them,
being replaced by fixes in code when possible.
Unit tests were failing on MSSQL. gc_collect_cycles() was
removed from the phpunit utils.php file to save time in running
the tests, but MSSQL doesn't clean up open files as well as
other databases.
This patch includes the garbage collection for the unit tests
that require it.
Andrew Nicols