### 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.
}
	return substr(length() - p_len);
}
char32_t ::unicode_at(int p_idx) const {
	ERR_FAIL_INDEX_V(p_idx, length(), 0);
	return operator[](p_idx);
}
 ::indent(const  &p_prefix) const {
	 new_string;
	int line_start = 0;
	for (int i = 0; i < length(); i++) {
		const char32_t c = operator[](i);
		if (c == '\n') {
			if (i == line_start) {
				new_string += c; // 
			} else {
				new_string += p_prefix + substr(line_start, i - line_start + 1);
			}
			line_start = i + 1;
		}
	}
	if (line_start != length()) {
		new_string += p_prefix + substr(line_start);
	}
	return new_string;
}
 ::dedent() const {
	 new_string;
	 indent;
	bool has_indent = false;