### 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.
s = s + String("Day");
	CHECK(s == "Have a Nice Day");
}
TEST_CASE("[String] Testing size and length of string") {
	
	CHECK(String("Mellon").size() == 7);
	CHECK(String("Mellon1").size() == 8);
	
	CHECK(String("Mellon").length() == 6);
	CHECK(String("Mellon1").length() == 7);
	CHECK(String("Mellon2").length() == 7);
	CHECK(String("Mellon3").length() == 7);
}
TEST_CASE("[String] Testing for empty string") {
	CHECK(!String("Mellon").is_empty());
	
	CHECK(String("").is_empty());
	CHECK(String("").is_empty());
	CHECK(String("").is_empty());
}
TEST_CASE("[String] Contains") {
	String s = "C:\\Godot\\project\\string_test.tscn";
	CHECK(s.contains(":\\"));
	CHECK(s.contains("Godot"));
	CHECK(s.contains(String("project\\string_test")));
	CHECK(s.contains(String("\\string_test.tscn")));
	CHECK(!s.contains("://"));
	CHECK(!s.contains("Godoh"));
	CHECK(!s.contains(String("project\\string test")));
	CHECK(!s.contains(String("\\char_test.tscn")));