Log.AlwaysLogUnhandledExceptions and ErrorReporting.CallUserHandlerOnFatals off by default

By turning these off by default, we should match Zend behavior better on fatals with custom error handlers.

Few examples:
```
set_error_handler(function () { echo 'hello'; });
invalid();
```
This should produce only a fatal error message without calling user handler.

```
set_error_handler(function () { echo 'hello'; });
echo $invalid;
```
This should call user handler without producing notice message.

```
set_exception_handler(function () { echo 'hello'; });
throw new Exception();
```
This should call user handler without producing fatal error message.

Relates to #3019 and #4055.