Removed use function imports for mocked/stubbed functions, disabling phpcs import rule

While the rule is now disabled, it still is very much valuable to import most pure functions from the core
PHP scope, allowing us some marginal gains on anything that can be inlined by the engine (now or in future).

The rule does not allow selective exclusions, so we will need to keep it off for now.

src/Generator/DefaultTimeGenerator.php

@@ -27,7 +27,7 @@ use function dechex;
 use function hex2bin;
 use function is_int;
 use function pack;
-use function random_int;
+use function sprintf;
 use function str_pad;
 use function strlen;