Fix and clarify logic in test_play filter test

[emersonknapp]

The test was allowing the filter to be incorrect by not checking for the correct number of messages, while setting the filter in a way that was overridden by play_options_. This PR restructures the existing test to be more readable, clear in its intention, and correct in its final expectations.

This doesn't fix the API confusion - I want to do that but it will have to wait for the moment - in the meantime this change at least fixes the test. The Reader.set_filter call will always be overridden in rosbag2_transport.play, which uses PlayOptions.topics_to_filter.

Note to the reviewer - the most important part of this change is EXPECT_THAT(topics, SizeIs(0u)) on the filtered tests - it was SizeIs(Ge(0u)) which was essentially not testing the filter

[jaisontj]

Nit: We could do a SizeIs(Ge(1u) -> check for "Does atleast one message arrive"

[emersonknapp]

Gist: https://gist.githubusercontent.com/emersonknapp/532afc479a05ca8e823d55cd04b7ac9f/raw/324d2087b557a72928c09ff8c2166fbb3507c091/ros2.repos
BUILD args: --packages-up-to rosbag2_transport rosbag2_tests
TEST args: --packages-select rosbag2_transport rosbag2_tests
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/7995

• Linux
• Linux-aarch64
• macOS
• Windows

[emersonknapp]

Windows CI is currently broken in the infrastructure - see ros-infrastructure/ros2-cookbooks#30 - I don't want to be blocked by that, we can fix any issues that arise later, if they do come up

[clalancette]

Windows CI is currently broken in the infrastructure - see ros-infrastructure/ros2-cookbooks#30 - I don't want to be blocked by that, we can fix any issues that arise later, if they do come up

Just as a point of order; I might suggest not doing this. If any platform is going to fail, it is going to be Windows.