[lldb][NFC] Remove all `setUp` overrides that only call the parent implementation

Summary:
A lot of our tests copied the setUp code from our TestSampleTest.py:

```
    def setUp(self):
        # Call super's setUp().
        TestBase.setUp(self)
```

This code does nothing unless we actually do any setUp work in there, so let's remove all these method definitions.

Reviewers: labath, JDevlieghere

Reviewed By: labath

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D71454