chore: remove unused variables

[parthea]

Fixes warning from flake8 . --select F841

(py39) partheniou@partheniou-vm-2:~/git/google-api-python-client$ flake8 . --select F841
./describe.py:310:5: F841 local variable 'resource_name' is assigned to but never used
./describe.py:350:13: F841 local variable 'dname' is assigned to but never used
./googleapiclient/discovery.py:430:9: F841 local variable 'service' is assigned to but never used
./googleapiclient/discovery.py:431:5: F841 local variable 'e' is assigned to but never used
./samples/coordinate/coordinate.py:97:3: F841 local variable 'e' is assigned to but never used
./tests/test_mocks.py:206:13: F841 local variable 'activity' is assigned to but never used
./tests/test_http.py:326:13: F841 local variable 'json' is assigned to but never used
./tests/test_http.py:963:13: F841 local variable 'response' is assigned to but never used
./tests/test_http.py:1241:9: F841 local variable 's' is assigned to but never used
./tests/test_discovery.py:246:9: F841 local variable 'parameters' is assigned to but never used
./tests/test_discovery.py:443:9: F841 local variable 'service' is assigned to but never used
./tests/test_discovery.py:450:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:458:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:477:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:598:45: F841 local variable 'http' is assigned to but never used
./tests/test_discovery.py:671:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:682:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:695:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:980:13: F841 local variable 'zoo' is assigned to but never used
./tests/test_discovery.py:998:13: F841 local variable 'zoo' is assigned to but never used
./tests/test_discovery.py:1016:13: F841 local variable 'zoo' is assigned to but never used
./tests/test_discovery.py:1256:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:1332:13: F841 local variable 'plus' is assigned to but never used
./tests/test_discovery.py:1954:13: F841 local variable 'body' is assigned to but never used
./tests/test__auth.py:131:13: F841 local variable 'credentials' is assigned to but never used
./tests/test__auth.py:135:13: F841 local variable 'credentials' is assigned to but never used