[Docking] Feature: support for not needing to set dock instances

[jcarlosgm30]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#4415
Primary OS tested on	Ubuntu 22.04
Robotic platform tested on	Gazebo Simulation
Does this PR contain AI generated software?	No

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Description of contribution in a few bullet points

The changes made are as follows:

• Support for not needing to set dock_instances
• Improve some log messages in dock_database.cpp
• Comment the dock instances out from nav2_params

These changes enable the system to work in the following use cases:

• Setting the dock instances in the parameters or database yaml file.
• Not setting the dock instances in these files but using the dock pose in the action request or the reload database service.

Also, the reload database service is available in any case where at least one dock plugin has been defined.

Description of documentation updates required from your changes

• The documentation may need to be updated to reflect the "Not setting ..." use case.

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Future work that may be required in bullet points

• The unit tests may need to be updated to address new changes

For Maintainers:

• Check that any new parameters added are updated in docs.nav2.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[SteveMacenski]

Generally looks good! Just some small cleanup! You also may need to update some unit tests, currently the dock database tests are failing from these changes.

[SteveMacenski]

test_dock_database.gtest.missing_result Your changes still are making a test fail, I think you need to look into that, but otherwise this looks good to me! My guess is the change in error handling has made a test fail and then since we pass successfully for no-docks created, something tries to access an empty vector and thus crashes.

But you should look into why that test is failing to make sure its not something in the logic you changed either!

[jcarlosgm30]

Yes, that test fails because there is no dock plugin initialized so the /reload_database service will not be created.

The old logic was that the /reload_database service was only created when getDockPlugins and getDockInstances returned false. As we discussed, the new logic creates the /reload_database service whenever at least a dock plugin is initialized.

So I think it will be enough to initialize a dock plugin in the test.

[SteveMacenski]

Fabulous, thank you!