RichTextLabel incorrectly strips trailing whitespace if newline is present on right-aligned line

[milesturin]

Tested versions

• Reproducible in: v4.3.stable.official [77dcf97]

System information

Godot v4.3.stable - macOS 14.2.1 - Vulkan (Forward+) - integrated Apple M2 Pro - Apple M2 Pro (12 Threads)

Issue description

According to the docs:

"Unlike BBCode in HTML, leading/trailing whitespace is not removed by a RichTextLabel upon display. Duplicate spaces are also displayed as-is in the final output."

However, i've run into a bug where RichTextLabels will automatically strip trailing whitespace on right-aligned lines if they end in newline.

Steps to reproduce

1. Create a RichTextLabel
2. Set the layout transform size to 256x256
3. Enable BBCode
4. Set the text to [right]TEST [/right]. This will not strip the whitespace, and will display correctly
5. Add a newline. This will cause the previous line to no loner end in whitespace. If you add another [right]TEST [/right] line, it will display correctly as long as it is the last line in the textbox.

Minimal reproduction project (MRP)

N/A