Clean up WebViewFactory.getProvider error handling.

We were catching and ignoring exceptions when looking up the provider
factory method, because in the past the code fell back to calling the
provider constructor instead. However, this case was removed a while
ago, so now if the reflection fails the exception will be lost.

This isn't a big issue as it will still crash with a
NullPointerException when trying to call the method that wasn't found,
but it makes the cause of the problem less clear. Remove the extra
try-catch and just handle all exceptions thrown during the process of
creating the provider the same way.

Test: atest CtsWebkitTestCases
Change-Id: Ib2079e743a830a04a4117d782afa6eaaa26766df