Re-enable arrres.il test

Re-enable arrres.il test

arrres.il is a quesionable test case because it relies on finalizers being
run even though the JIT is allowed to extend the lifetime of objects
beyond the point where finalizer effects are checked.  The test could be
fixed, but for now I'm just marking it as requiring optimization, which is
what has been done previously.  I'm deleting the "dbg" project because it
is the same as the "rel" project except that it disables optimization.

Fixes dotnet/coreclr#2330

Commit migrated from https://github.com/dotnet/coreclr/commit/195baf674a92c7ddb0ba4dac425abf1a8b0402cf