### Godot version

4.0 beta 15

### System information

Windows 10

### Issue description

It happened with both Google IME and MS-IME, and there was no problem until Beta14.
When typing Japanese characters, it is common to select a character from the suggestion window and then start typing the next character before confirming.
In this case, uncommitted characters are forcibly committed, and input of the next character begins.

**↓Beta15**

https://user-images.githubusercontent.com/186786/214753450-b493cca6-2644-4b3d-8cd2-660565cc3547.mp4

**↓Beta14**

https://user-images.githubusercontent.com/186786/214755127-dde819cc-4d63-403a-99b0-09821671f74e.mp4



### Steps to reproduce

It happened with both Google IME and MS-IME in beta15

### Minimal reproduction project

It is project independent and happens in the editor.
if (p_key.length() == 0) {
		return Point2(-1, -1);
	}
	ERR_FAIL_INDEX_V(p_from_line, text.size(), Point2i(-1, -1));
	ERR_FAIL_INDEX_V(p_from_column, text[p_from_line].length() + 1, Point2i(-1, -1));
	
	int line = p_from_line;
	int pos = -1;
	for (int i = 0; i < text.size() + 1; i++) {
		if (line < 0) {
			line = text.size() - 1;
		}
		if (line == text.size()) {
			line = 0;
		}
		String text_line = text[line];
		int from_column = 0;
		if (line == p_from_line) {
			if (i == text.size()) {
				
				if (p_search_flags & SEARCH_BACKWARDS) {
					from_column = text_line.length();
				} else {
					from_column = 0;
				}
			} else {
				from_column = p_from_column;
			}
		} else {