Increase margin for state_publish_rate

[christophfroehlich]

The test is flaky, often only 8 messages are received.

Fixes #1116.

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 66.77%. Comparing base (0e6f08b) to head (c4dbfc9).
Report is 2 commits behind head on humble.

Files with missing lines	Patch %	Lines
...ory_controller/test/test_trajectory_controller.cpp	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           humble    #1430      +/-   ##
==========================================
+ Coverage   66.75%   66.77%   +0.02%     
==========================================
  Files         113      113              
  Lines       13335    13338       +3     
  Branches     8242     8240       -2     
==========================================
+ Hits         8902     8907       +5     
  Misses       1442     1442              
+ Partials     2991     2989       -2     

Flag	Coverage Δ
unittests	66.77% <75.00%> (+0.02%)	⬆️

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

Files with missing lines	Coverage Δ
...ory_controller/test/test_trajectory_controller.cpp	70.62% <75.00%> (+0.08%)	⬆️

... and 1 file with indirect coverage changes