Exclude failing sub-tests in Wycheproof job

We need to figure out the way to exclude failing wycheproof tests from the build job. [Wycheproof documentation](https://github.com/google/wycheproof), [Bazel manual](https://docs.bazel.build/versions/master/user-manual.html) does not seem to document a simple way. Need to investigate.

Start by locating the Wycheproof build job and its Bazel configuration, then read the linked Wycheproof documentation and Bazel manual for supported exclusion mechanisms. Done means the build job reliably excludes the failing sub-tests without masking other test failures.

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