Compiler ICE caused by invalid type unification of arrays

[ironcev]

#7601 introduces a should_pass/language/const_generics_array_in_reassignments tests with the following code snippet:

    array.default_self(42);       //  <<<<---- `array` is of type `[u8;3]`.
    assert_eq([42u8; 3], array);  //  <<<<---- This works as expected.
    assert_eq([42; 3], array);    //  <<<<---- This causes ICE.

where default_self is defined as:

impl<T, const N: u64> DefaultSelf<T> for [T; N]
where
    T: AbiEncode + PartialEq,
{
    fn default_self(ref mut self, default: T) {
        ...
    }
}

Calling assert_eq without explicitly specifying the type causes:

error: Internal compiler error: Verification failed: init_aggr instruction has an initializer with a type mismatch for array element at index 0. Expected element type: u8, found initializer type: u64.