This just asserts that web services provided by deprecated plugins can
still be used (similar to how their APIs can still be used during the
deprecation period).
This fixes various (not all) wrong @covers annotations that
are reported as warnings by PHPUnit when it's run with
code-coverage enabled.
When possible, the preferred solution is to change to
@covers at class level, that is the recommended way.
If multiple classes are involved, then a mix of @coversDefaultClass
and @covers at method level are used (always trying to use the
minimum needed patch).
This is the first of a series of issues created as sub-tasks
of MDL-82142.