[RTPublisher] use NON_POLLING as default for the realtime pubisher (backport #280)

[mergify]

Fixes: #212

As reported by @bijoua29

I ran some tests with non-polling in some controllers and perf doesn't even report the sleep anymore. Most of the work is now in the DDS publish() method.

I did another test where I compiled realtime_tools from source and set it to non-polling. When I ran my full stack, the CPU usage of ros2 control node reduced from ~75% to ~52% CPU i.e. around a 30% reduction in CPU usage. Note: this is percent of 1 CPU so since I have 32 CPUs the actual usage is 1/32 of that.

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This is an automatic backport of pull request #280 done by Mergify.

[mergify]

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Changes to be committed:
	modified:   include/realtime_tools/realtime_publisher.hpp
	deleted:    test/realtime_publisher_non_polling.test
	deleted:    test/realtime_publisher_tests_non_polling.cpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   CMakeLists.txt

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.

Project coverage is 70.23%. Comparing base (02d6794) to head (0835663).

Files with missing lines	Patch %	Lines
include/realtime_tools/realtime_publisher.hpp	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            jazzy     #282      +/-   ##
==========================================
- Coverage   70.72%   70.23%   -0.49%     
==========================================
  Files           9        9              
  Lines         526      514      -12     
  Branches       87       84       -3     
==========================================
- Hits          372      361      -11     
+ Misses         99       98       -1     
  Partials       55       55              

Flag	Coverage Δ
unittests	70.23% <87.50%> (-0.49%)	⬇️

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

Files with missing lines	Coverage Δ
include/realtime_tools/realtime_publisher.hpp	97.67% <87.50%> (+1.31%)	⬆️