### 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.
COUNT_TEST(String("Test").count("TEST") == 0);
	COUNT_TEST(String("TEST").count("TEST") == 1);
	COUNT_TEST(String("Test").count("Test") == 1);
	COUNT_TEST(String("aTest").count("Test") == 1);
	COUNT_TEST(String("Testa").count("Test") == 1);
	COUNT_TEST(String("TestTestTest").count("Test") == 3);
	COUNT_TEST(String("TestTestTest").count("TestTest") == 1);
	COUNT_TEST(String("TestGodotTestGodotTestGodot").count("Test") == 3);
	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 8) == 1);
	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 12) == 2);
	COUNT_TEST(String("TestTestTestTest").count("Test", 4, 16) == 3);
	COUNT_TEST(String("TestTestTestTest").count("Test", 4) == 3);
	COUNT_TEST(String("Test").countn("test") == 1);
	COUNT_TEST(String("Test").countn("TEST") == 1);
	COUNT_TEST(String("testTest-Testatest").countn("tEst") == 4);
	COUNT_TEST(String("testTest-TeStatest").countn("tEsT", 4, 16) == 2);
	CHECK(state);
#undef COUNT_TEST
}
TEST_CASE("[String] Bigrams") {
	String s = "abcd";
	Vector<String> bigr = s.bigrams();
	CHECK(bigr.size() == 3);
	CHECK(bigr[0] == "ab");
	CHECK(bigr[1] == "bc");
	CHECK(bigr[2] == "cd");
}
TEST_CASE("[String] c-escape/unescape") {
	String s = "\\1\a2\b\f3\n45\r6\t7\v8\'9\?0\"";
	CHECK(s.c_escape().c_unescape() == s);