### 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 (in_decimals) {
						return "too many decimal points in format";
					}
					in_decimals = true;
					min_decimals = 0; // 
					break;
				}
				case '*': { // 
					if (value_index >= values.size()) {
						return "not enough arguments for format string";
					}
					Variant::Type value_type = values[value_index].get_type();
					if (!values[value_index].is_num() &&
							value_type != Variant::VECTOR2 && value_type != Variant::VECTOR2I &&
							value_type != Variant::VECTOR3 && value_type != Variant::VECTOR3I &&
							value_type != Variant::VECTOR4 && value_type != Variant::VECTOR4I) {
						return "* wants number or vector";
					}
					int size = values[value_index];
					if (in_decimals) {
						min_decimals = size;
					} else {
						min_chars = size;
					}
					++value_index;
					break;
				}
				default: {
					return "unsupported format character";
				}