Remove no_bazel_downstream tag filter (#1830)

There is no good way to introduce this tag filter without overriding
existing ones in the bazelrc files.

This has been causing a few failures in the downstream pipeline:
https://github.com/bazelbuild/bazel/issues/20422, where `//src:src_test`
is supposed to be filtered out on Windows by `no_windows` tag.
2 files changed