Replace use of the deprecated newInstance() method

[DomGarguilo]

While working on #150 I noticed the following while building:

[WARNING] /home/dgarguilo/github/accumulo-testing/src/main/java/org/apache/accumulo/testing/scalability/Run.java:[83,9] newInstance() in java.lang.Class has been deprecated

It looks like newInstance() has been deprecated and replaced by getDeclaredConstructor().newInstance().

[milleruntime]

The Scalability test is pretty old and I don't know of anyone that has run the test in a while. It might be worth it as a follow on to run it and update it. It may be still be a useful test.

[DomGarguilo]

The Scalability test is pretty old and I don't know of anyone that has run the test in a while. It might be worth it as a follow on to run it and update it. It may be still be a useful test.

I'll go ahead and merge this for now then take a closer look at the scalability test. Was there anything in particular you had in mind in terms of updating it?

[milleruntime]

The Scalability test is pretty old and I don't know of anyone that has run the test in a while. It might be worth it as a follow on to run it and update it. It may be still be a useful test.

I'll go ahead and merge this for now then take a closer look at the scalability test. Was there anything in particular you had in mind in terms of updating it?

Mostly just test to make sure it still works. I took a quick look at the classes and one thing we could do is make a helper script in <testing-home>/bin like we do with the other tests. That would make it easier to run at least.