[clang] Remove overly restrictive aggregate paren init logic

[clang] Remove overly restrictive aggregate paren init logic

Previously, we would only attempt to perform a parenthesized aggregate
initialization if constructor initialization failed for only the default
constructor, default copy constructor, and default move constructor. The
original intent of this logic was to reject initializing objects that
have failed resolving a user-defined constructor. However, this check is
redundant because we check for isAggregate() before attempting to
perform a parenthesized aggregate initialization, and classes that have
user-defined or user-declared constructors are not aggregates.
Furthermore, this check is too restrictive - the following valid
examples fail:
* Aggregate class with user-defined destructor - fails because default
  move constructors are not generated for classes with user-defined
  destructors
  (https://github.com/llvm/llvm-project/issues/54040#issuecomment-1356926048)
* Concept-guarded conversion operator on an aggregate's member:
  (https://github.com/llvm/llvm-project/issues/54040#issuecomment-1356931745)

The solution therefore is to remove this logic; existing tests still
pass, and the previously failing examples now compile.

Reviewed By: ilya-biryukov

Differential Revision: https://reviews.llvm.org/D140327