[NFC][LLDB] Rename test file

Commit 92f0e4cca introduced test file with name TestChangeValue.py,
which leads to test failure because there already is a test files with the same name
In this commit a newly added file is renamed to fix this failure

diff --git a/lldb/test/API/python_api/value/change_values/libcxx/map/TestChangeValue.py b/lldb/test/API/python_api/value/change_values/libcxx/map/TestChangeMapValue.py
similarity index 100%
rename from lldb/test/API/python_api/value/change_values/libcxx/map/TestChangeValue.py
rename to lldb/test/API/python_api/value/change_values/libcxx/map/TestChangeMapValue.py