### 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.
struct StringCasesTestCase {
	const char *input;
	const char *camel_case;
	const char *pascal_case;
	const char *snake_case;
};
TEST_CASE("[String] Checking case conversion methods") {
	StringCasesTestCase test_cases[] = {
		
		{ "2D",                "2d",              "2d",              "2d"                },
		{ "2d",                "2d",              "2d",              "2d"                },
		{ "2db",               "2Db",             "2Db",             "2_db"              },
		{ "Vector3",           "vector3",         "Vector3",         "vector_3"          },
		{ "sha256",            "sha256",          "Sha256",          "sha_256"           },
		{ "Node2D",            "node2d",          "Node2d",          "node_2d"           },
		{ "RichTextLabel",     "richTextLabel",   "RichTextLabel",   "rich_text_label"   },
		{ "HTML5",             "html5",           "Html5",           "html_5"            },
		{ "Node2DPosition",    "node2dPosition",  "Node2dPosition",  "node_2d_position"  },
		{ "Number2Digits",     "number2Digits",   "Number2Digits",   "number_2_digits"   },
		{ "get_property_list", "getPropertyList", "GetPropertyList", "get_property_list" },
		{ "get_camera_2d",     "getCamera2d",     "GetCamera2d",     "get_camera_2d"     },
		{ "_physics_process",  "physicsProcess",  "PhysicsProcess",  "_physics_process"  },
		{ "bytes2var",         "bytes2Var",       "Bytes2Var",       "bytes_2_var"       },
		{ "linear2db",         "linear2Db",       "Linear2Db",       "linear_2_db"       },
		{ "sha256sum",         "sha256Sum",       "Sha256Sum",       "sha_256_sum"       },
		{ "camelCase",         "camelCase",       "CamelCase",       "camel_case"        },
		{ "PascalCase",        "pascalCase",      "PascalCase",      "pascal_case"       },
		{ "snake_case",        "snakeCase",       "SnakeCase",       "snake_case"        },
		{ "Test TEST test",    "testTestTest",    "TestTestTest",    "test_test_test"    },
		{ nullptr,             nullptr,           nullptr,           nullptr             },