Remove the tempest/tests/negative/ directory

It's empty and useless, let's just delete it.

Change-Id: I017b3ab3b9c74f8d860da53581ea86b65df48f87
diff --git a/tempest/tests/negative/__init__.py b/tempest/tests/negative/__init__.py
deleted file mode 100644
index e69de29..0000000
--- a/tempest/tests/negative/__init__.py
+++ /dev/null