### Godot version

4.2.beta.custom_build [51f81e1c8]

### System information

macOS 11.0+

### Issue description

I could sense a recent merging of a few pull requests on here:

<img width="865" alt="image" src="https://github.com/godotengine/godot/assets/1129695/1cf7d144-a4d2-4514-abca-1405222e702a">

This bug has the following related merges as the most recent ones:

https://github.com/godotengine/godot/pull/80813
https://github.com/godotengine/godot/pull/80939

The pull requests are for reviving onion-skinning capabilities, but this causes a minor unexpected result (see Steps to reproduce)



### Steps to reproduce

## A. Use 4.2.beta.custom_build [51f81e1c8]

1. Obtain the attached minimal reproduction project
2. Select the AnimationPlayer node
<img width="1468" alt="image" src="https://github.com/godotengine/godot/assets/1129695/ca16d7a6-7690-45b4-b8f9-b12fded64ca4">
3. In the Animation panel, click "Edit" to find your shortcuts for "Go to Next Step" and "Go to Previous Step"
<img width="410" alt="image" src="https://github.com/godotengine/godot/assets/1129695/a708e196-2eb9-42ea-bf0e-fd0aa88a9e60">
4. Use the shortcuts to spam go back and forth the animation

Expected result: animation goes smoothly

https://github.com/godotengine/godot/assets/1129695/c24c498c-7f77-4cc9-a1c9-a1627d89c58b



Actual result: animation jumps crazily


https://github.com/godotengine/godot/assets/1129695/947bf5b4-a0ab-42d4-bb5b-201800b4bdc6


https://github.com/godotengine/godot/assets/1129695/65303cd0-8c2d-4a35-9d16-c94752ac2e3a




## B. My successful yet unverified fix attempt on 4.2.beta.custom_build [51f81e1c8]

Either by:

<img width="831" alt="image" src="https://github.com/godotengine/godot/assets/1129695/80d167ae-27e7-4ec4-a4c9-ffc7adc0353f">


Or by:

<img width="806" alt="image" src="https://github.com/godotengine/godot/assets/1129695/2bae8697-8ef3-48dc-9f0a-2b5fe568ed43">


I don't see any negative impact on Onion Skinning or other functions by the above fix attempt, but I am not sure, I need someone to help me verify this.



### Minimal reproduction project

[gd_anim_unittest_1.zip](https://github.com/godotengine/godot/files/12909805/gd_anim_unittest_1.zip)






int frame = pos / step_size;
						int prev_frame = prev / step_size;
						bool sub = Math::floor(prev) == Math::floor(pos);
						if (frame != prev_frame && i >= prev_frame_ofs) {
							draw_line(Point2(get_name_limit() + i, 0), Point2(get_name_limit() + i, h), linecolor, Math::round(EDSCALE));
							draw_string(font, Point2(get_name_limit() + i + 3 * EDSCALE, (h - font->get_height(font_size)) / 2 + font->get_ascent(font_size)).floor(), itos(frame), HORIZONTAL_ALIGNMENT_LEFT, zoomw - i, font_size, sub ? color_time_dec : color_time_sec);
							prev_frame_ofs = i + font->get_string_size(itos(frame), HORIZONTAL_ALIGNMENT_LEFT, -1, font_size).x + 5 * EDSCALE;
						}
					}
				}
			} else {
				for (int i = 0; i < zoomw; i++) {
					float pos = get_value() + double(i) / scale;
					float prev = get_value() + (double(i) - 1.0) / scale;
					int sc = int(Math::floor(pos * SC_ADJ));
					int prev_sc = int(Math::floor(prev * SC_ADJ));
					bool sub = (sc % SC_ADJ);
					if ((sc / step) != (prev_sc / step) || (prev_sc < 0 && sc >= 0)) {
						int scd = sc < 0 ? prev_sc : sc;
						draw_line(Point2(get_name_limit() + i, 0), Point2(get_name_limit() + i, h), linecolor, Math::round(EDSCALE));
						draw_string(font, Point2(get_name_limit() + i + 3, (h - font->get_height(font_size)) / 2 + font->get_ascent(font_size)).floor(), String::num((scd - (scd % step)) / double(SC_ADJ), decimals), HORIZONTAL_ALIGNMENT_LEFT, zoomw - i, font_size, sub ? color_time_dec : color_time_sec);
					}
				}
			}
			draw_line(Vector2(0, get_size().height), get_size(), linecolor, Math::round(EDSCALE));
			update_values();
		} break;
	}
}
void AnimationTimelineEdit::set_animation(const Ref<Animation> &p_animation, bool p_read_only) {