Attach debug info outputs to rust tests

[chancila]

Unclear why #1072 explicitly didn't allow tests to generate dsym files via the dsym_folder output group.

This change allows them to do so and make debugging easier on macos.

Manual verification on macos:

bazel build -c dbg //test/unit/debug_info:myrusttest
rust-lldb bazel-bin/test/unit/debug_info/test-2282882243/myrusttest \
    --one-line "image list" \
    --one-line "exit" | \
    grep DWARF &>/dev/null && echo "dSYM module loaded"

should print dSYM module loaded

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[illicitonion]

LGTM, thanks!

@ddeville I think you added this originally - was there an important reason to skip debug generation for tests?