manual keyword will force the test target to not be included in target pattern wildcards (..., :*, :all, etc); the test target will be neither built nor run. It will also be ignored by the test_suite rules that do not mention this test explicitly. The only way to build or run such a test is to specify it via an explicit target pattern on the command line.
"manual" has the effect we want. See https://docs.bazel.build/versions/master/be/common-definitions.html#common-attributes