Keys that are beyond the Animation length don't get evaluated

### Tested versions

4.3.stable
Master - Godot v4.4.beta (172fc62c8)

### System information

Godot v4.4.beta (172fc62c8) - Windows 11 (build 22631) - Multi-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 4070 Laptop GPU (NVIDIA; 32.0.15.6614) - AMD Ryzen 7 7840HS w/ Radeon 780M Graphics (16 threads)

### Issue description

If a key is beyond the end of the animation it is no longer evaluated. This is the same in both value and bezier tracks.

This feels like a bug as keys that are before the beginning of the animation (i.e. in negative time) do get evaluated and there is no indication in the animation player that the key will not be evaluated, such as greying out the key / curve.

https://github.com/user-attachments/assets/ae06f5f8-b58a-4e34-a991-24ef95d1210c

### Steps to reproduce

Create an animation where one of the keys is beyond the end of the animation.

### Minimal reproduction project (MRP)

NA

Start by reproducing the issue in Godot's AnimationPlayer with both value and bezier tracks, using keys placed beyond the animation length and before time zero. Trace the animation evaluation path for these tracks; done means keys beyond the end are evaluated consistently with keys before the beginning, or the editor clearly indicates that they are excluded.

Written by the indexing model from the issue text.