### 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.
CHECK(a.naturalnocasecmp_to("img10.png") < 0);
}
TEST_CASE("[String] hex_encode_buffer") {
	static const uint8_t u8str[] = { 0x45, 0xE3, 0x81, 0x8A, 0x8F, 0xE3 };
	String s = String::hex_encode_buffer(u8str, 6);
	CHECK(s == U"45e3818a8fe3");
}
TEST_CASE("[String] Substr") {
	String s = "Killer Baby";
	CHECK(s.substr(3, 4) == "ler ");
	CHECK(s.substr(3) == "ler Baby");
}
TEST_CASE("[String] Find") {
	String s = "Pretty Woman Woman";
	CHECK(s.find("tty") == 3);
	CHECK(s.find("Wo", 9) == 13);
	CHECK(s.find("Revenge of the Monster Truck") == -1);
	CHECK(s.rfind("man") == 15);
}
TEST_CASE("[String] Find no case") {
	String s = "Pretty Whale Whale";
	CHECK(s.findn("WHA") == 7);
	CHECK(s.findn("WHA", 9) == 13);
	CHECK(s.findn("Revenge of the Monster SawFish") == -1);
	CHECK(s.rfindn("WHA") == 13);
}
TEST_CASE("[String] Find MK") {
	Vector<String> keys;
	keys.push_back("sty");
	keys.push_back("tty");