test: Unify mongo instrumentation for 1.3.19+

Now, the 1.3.19 test is simply a symlink to the 1.4.0 test.
test: Update mongo tests to ensure segments are properly ended
test: Remove unused multiverse tests
mongo: Improve find instrumentation

The old instrumentation tried to monitor calls to Collection.find(), but
the real work is done from iterator methods on the Cursor object that
find() returns. This new implementation of the find instrumentation
ensures we end all segments after finishing result iterations (whether
through .toArray(), .each(), calling .nextObject() to exhaustion, or
calling Cursor.close()). It also does a better job of determining when
subsequent new operations are performed vs internal recursive calling of
operations.
docs: updated for new version
release: published 1.11.1