### 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.
static const double num[4] = { -12348298412.2, 0.05, 2.0002, -0.0001 };
	for (int i = 0; i < 4; i++) {
		CHECK(!(ABS(String(nums[i]).to_float() - num[i]) > 0.00001));
	}
}
TEST_CASE("[String] Slicing") {
	String s = "Mars,Jupiter,Saturn,Uranus";
	const char *slices[4] = { "Mars", "Jupiter", "Saturn", "Uranus" };
	for (int i = 0; i < s.get_slice_count(","); i++) {
		CHECK(s.get_slice(",", i) == slices[i]);
	}
}
TEST_CASE("[String] Splitting") {
	String s = "Mars,Jupiter,Saturn,Uranus";
	Vector<String> l;
	const char *slices_l[3] = { "Mars", "Jupiter", "Saturn,Uranus" };
	const char *slices_r[3] = { "Mars,Jupiter", "Saturn", "Uranus" };
	const char *slices_3[4] = { "t", "e", "s", "t" };
	l = s.split(",", true, 2);
	CHECK(l.size() == 3);
	for (int i = 0; i < l.size(); i++) {
		CHECK(l[i] == slices_l[i]);
	}
	l = s.rsplit(",", true, 2);
	CHECK(l.size() == 3);
	for (int i = 0; i < l.size(); i++) {
		CHECK(l[i] == slices_r[i]);
	}
	s = "test";
	l = s.split();