Add loop and sleep to test

[gbiggs]

Bug fix

Fixed bug

One of the tests in test_Transport.cpp in rmf_rxcpp was flaky due to a race condition between creating a subscriber to a topic and checking the count of subscribers to that topic. See here for one example of where this was failing.

Fix applied

A loop was added that sleeps briefly then checks if the subscription has been created. When the subscription exists the loop exits. The loop is limited to 10 iterations.

[mxgrey]

There's a tiny code linting error.

[gbiggs]

@mxgrey The test that's failing appears to be unrelated to the changes in this PR.

[codecov]

Codecov Report

Merging #109 (e3baa36) into main (fb9f934) will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #109      +/-   ##
==========================================
+ Coverage   21.48%   21.54%   +0.05%     
==========================================
  Files         211      844     +633     
  Lines       17153    68628   +51475     
  Branches     8129    32524   +24395     
==========================================
+ Hits         3686    14784   +11098     
- Misses       9507    37996   +28489     
- Partials     3960    15848   +11888     

Flag	Coverage Δ
tests	21.54% <ø> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...apter/src/rmf_fleet_adapter/services/Negotiate.hpp
...adapter/src/rmf_fleet_adapter/phases/MoveRobot.hpp
...fleet_adapter/src/rmf_fleet_adapter/estimation.cpp
...xCpp-4.1.0/Rx/v2/src/rxcpp/operators/rx-concat.hpp
...f_fleet_adapter/agv/internal_RobotUpdateHandle.hpp
.../RxCpp-4.1.0/Rx/v2/src/rxcpp/operators/rx-lift.hpp
.../rmf_task_ros2/test/dispatcher/test_Dispatcher.cpp
...Cpp-4.1.0/Rx/v2/src/rxcpp/subjects/rx-behavior.hpp
...d4xr/rmf_ros2/rmf_fleet_adapter/test/test_Task.cpp
...s2/src/rmf_traffic_ros2/geometry/ShapeInternal.hpp
... and 1045 more