Fix logging lifecycles and clean up tests

[mxgrey]

This PR addresses two points of feedback:

• Make sure that logging is only configured once and only fini-ed when all contexts are gone [1]
• Use ENTITY_LIFECYCLE_MUTEX to protect against race conditions [2]

While making this PR I uncovered a fault in one of the tests which didn't show up because of the flawed teardown of logging: The empty graph tests should now show that a /rosout node exists and that it has one topic.

I also took the liberty of cleaning up the tests to make sure that each test creates a node with a unique name, because otherwise we get spammed with warnings which might mislead someone into thinking that something is wrong with rclrs or its tests.

[geoff-imdex]

Nice work! Appreciate the fix for the graph test - not sure why this didn't fail for me originally, but we started seeing it in some additional work we've been doing.

[geoff-imdex]

As with unboxed_logging, merging this in with the build failing to make it easier to spin up a new branch/pr to address.