[lldb] Fix a typo in a test name

Summary:
Removing the Test prefix from the file name and its usages. The standard is using only Test as a suffix.
This was correctly pointed out in https://reviews.llvm.org/D77444.

Reviewers: labath, clayborg

Subscribers: mgorny, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D77878