Remove AMD CPU CI

.gitlab-ci.yml

-"Python 2.7 AMD CPU":
-  script:
-  - export PY_EXE=python2.7
-  - export PYOPENCL_TEST=amd:pu
-  - export EXTRA_INSTALL="pybind11 numpy mako"
-  - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
-  - ". ./build-and-test-py-project.sh"
-  allow_failure: true
-  tags:
-  - python2.7
-  - amd-cl-cpu
-  - opengl
-  except:
-  - tags
-  artifacts:
-    reports:
-      junit: test/pytest.xml
-
 Python 3 Intel CPU:
   script:
   - export PY_EXE=python3