### Godot version

v4.1.stable.official [970459615]

### System information

Windows 11

### Issue description

Using `String::pad_zeros` on a string containing digits with greater length than the argument `digits` raises the error `Parameter count should be a positive number.` of `String::repeat`, because it is called with a negative parameter.
(Actually this error is not 100% correct, it should be non-negative)

4.0 Code:
https://github.com/godotengine/godot/blob/c8e0bd50c57de91c061866db1de407f2e7a74acd/core/string/ustring.cpp#L4127-L4155

Example: `"2023".pad_zeros(2)`
`begin == 0`
`end == 4`
`end - begin < p_digits == false` => No "0" is inserted, the string is returned unchanged.

4.1 Code:
https://github.com/godotengine/godot/blob/ce5c6151fc498b39fe0c188045a4685e0f627854/core/string/ustring.cpp#L4266-L4290

Example: `"2023".pad_zeros(2)`
`begin == 0`
`end == 4`
`zeros_to_add == 2 - (4 - 0) == -2`
=> `s.insert(0, String("0").repeat(-2))` is called => Error.

I don't know why this was changed, but I think ensuring that `zeros_to_add > 0` should be ensured internally and not by the user. If this condition is not fullfilled the string should be returned unchanged as in the 4.0 implementation.

### Steps to reproduce

Try my above mentioned example in 4.0 and 4.1

### Minimal reproduction project

Not necessary.
if (p_len == 0 || !p_str[0]) {
		return 0;
	}
	//
	int64_t integer = 0;
	int64_t sign = 1;
	int reading = READING_SIGN;
	const char32_t *str = p_str;
	const char32_t *limit = &p_str[p_len];
	while (*str && reading != READING_DONE && str != limit) {
		char32_t c = *(str++);
		switch (reading) {
			case READING_SIGN: {
				if (is_digit(c)) {
					reading = READING_INT;
					// 
				} else if (c == '-') {
					sign = -1;
					reading = READING_INT;
					break;
				} else if (c == '+') {
					sign = 1;
					reading = READING_INT;
					break;
				} else {
					break;
				}
				[[fallthrough]];