GPL custom validator: Use tl_expected from libexpected-dev instead (backport #2212)

[mergify]

Needs PickNikRobotics/generate_parameter_library#322

and reverts #2127

---

This is an automatic backport of pull request #2212 done by Mergify.

[mergify]

Cherry-pick of 813ed25 has failed:

On branch mergify/bp/humble/pr-2212
Your branch is up to date with 'origin/humble'.

You are currently cherry-picking commit 813ed25.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   joint_trajectory_controller/package.xml

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

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]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.54%. Comparing base (21f96d9) to head (0f40b8b).
⚠️ Report is 3 commits behind head on humble.

Additional details and impacted files

@@           Coverage Diff           @@
##           humble    #2238   +/-   ##
=======================================
  Coverage   67.54%   67.54%           
=======================================
  Files         126      126           
  Lines       14391    14391           
  Branches     9155     9156    +1     
=======================================
  Hits         9721     9721           
- Misses       1408     1414    +6     
+ Partials     3262     3256    -6     

Flag	Coverage Δ
unittests	67.54% <ø> (ø)

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

Files with missing lines	Coverage Δ
..._trajectory_controller/validate_jtc_parameters.hpp	75.75% <ø> (ø)

... and 1 file with indirect coverage changes

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