### 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.
for (int i = 0; i < len; i++) {
		if (!_is_valid_identifier_bit(i, str[i])) {
			return false;
		}
	}
	return true;
}
bool ::is_valid_string() const {
	int l = length();
	const char32_t *src = get_data();
	bool valid = true;
	for (int i = 0; i < l; i++) {
		valid = valid && (src[i] < 0xd800 || (src[i] > 0xdfff && src[i] <= 0x10ffff));
	}
	return valid;
}
 ::uri_encode() const {
	const Char temp = utf8();
	 res;
	for (int i = 0; i < temp.length(); ++i) {
		uint8_t ord = temp[i];
		if (ord == '.' || ord == '-' || ord == '~' || is_ascii_identifier_char(ord)) {
			res += ord;
		} else {
			char p[4] = { '%', 0, 0, 0 };
			static const char hex[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
			p[1] = hex[ord >> 4];
			p[2] = hex[ord & 0xF];
			res += p;
		}