Use the active extruder's retraction after a tool change

[JATMN (jatmn)]

Description

This fixes the travel retraction that follows a tool change in the middle of a layer. The length and speed stayed on the previous extruder when the current mesh still belonged to that extruder, which is what mesh-less travels such as support were using. A later layer that already starts on the new extruder was unaffected.

The switch retraction itself still uses the previous extruder's switch retraction. After that switch, later travels use the active extruder's retraction distance, speed, and hop height.

Fixes #1866. The same report is tracked in Ultimaker/Cura#15043.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• LayerPlanTest.TravelRetractionUsesActiveExtruderAfterToolChange fails on main with G1 F2400 E-3 after T1, and passes with F1500 and E-10 for the newly active extruder.
• The full LayerPlanTest binary: 1444 tests passed.

Test Configuration:

• Operating System: Debian 13, gcc 14.2, local Release build with Arcus and plugins disabled

Checklist:

• My code follows the style guidelines of this project as described in UltiMaker Meta
• I have read the Contribution guide
• I have commented my code, particularly in hard-to-understand areas
• I have uploaded any files required to test this change