Closes phpstan/phpstan#6872

The problem is

1. It all starts with a UnionType::accepts with a CompoundType like e.g. TemplateObjectWithoutClassType
2. UnionType::accepts calls accepts on all inner types via https://github.com/phpstan/phpstan-src/blob/1.4.7/src/Type/UnionType.php#L104
3. If there is a FloatType in the union, then it would call CompoundType::isAcceptedBy with a newly created float|int union
4. the changes introduced in 35606f9 would call UnionType::accepts (the new float|int one) via 35606f9#diff-9085cfd032ca2e4178b6ba4ba9815c7bfffba6f2d5c0cfd06e29d3cb75fa0ecfR123
5. it starts from 1. again

I digged some more, apparently this was introduced in adb4fdd together with tests. And those tests are still there and green, see https://github.com/phpstan/phpstan-src/blob/1.4.x/tests/PHPStan/Type/FloatTypeTest.php. So the FloatType still accepts int and float and int|float. I think this should be fine then.