Use different Vulcanexus images for each Fast DDS version

[cferreiragonz]

This PR selects the Vulcanexus base image used for testing according the Fast DDS version used.

It also removes the temporary workaround introduced in #510 to fix ROS 2 apt keys.

It must be merged after rebuilding all docker images.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 30.24%. Comparing base (8abc3d8) to head (5ad4819).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #512      +/-   ##
==========================================
- Coverage   31.14%   30.24%   -0.90%     
==========================================
  Files          16       16              
  Lines         594      562      -32     
  Branches      321      298      -23     
==========================================
- Hits          185      170      -15     
+ Misses        213      205       -8     
+ Partials      196      187       -9     

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[cferreiragonz]

Arguments were checked here and here.

[cferreiragonz]

New CI tests:

• Jazzy (Fast 3.x): https://github.com/eProsima/DDS-Router/actions/runs/15772928949/job/44461052278
• Humble (Fast 2.x): https://github.com/eProsima/DDS-Router/actions/runs/15772976885/job/44461192405
  All the CI in Humble is gonna failed as I used the 'v2' artifact and tried to build this branch, which must use Fast DDS 3. However, the arguments passed were pointing to 2.x branch so the Vulcanexus base image selected was humble-core, which is correct.

[EugenioCollado]

LGTM