Use new name for ArduPlane RTL altitude in all Safety components

[Maarrk]

Description

Use the correct RTL_ALTITUDE parameter for ArduPlane > 4.5.

Reuses logic introduced to other QML files referencing ALT_HOLD_RTL.
It was originally done in 2db7285 PR #12195, but this file wasn't changed then.

Test Steps

1. Connect ArduPlane 4.6 or newer
2. Open QGC logo -> Vehicle Configuration -> Safety
3. Set "Return at specified altitude:" to some positive value
4. Open Summary tab
5. Check the value in "RTL min alt:" row - should be the same as set in step 3, but is missing without this fix

Checklist:

• Review Contribution Guidelines.
• Review Code of Conduct.
• I have tested my changes.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Contribution on behalf of @FlyfocusUAV

[DonLakeFlyer]

So in looking at this, both this change and #12195 were not done correctly. They should be using the built in FirmwarePlugin::paramNameRemapMajorVersionMap functionality to provide parameter name remapping between versions. This way the qml code only needs to be updated once to use the "r.FOO" variants of parameter names and then the FirmwarePlugin will switch to the right parameter name based on firmware version.

[Maarrk]

Thanks @DonLakeFlyer! I'll update this and have a look for other spots where this should be changed.

[DonLakeFlyer]

I'll update this and have a look for other spots where this should be changed.

Awesome, thanks so much