Run TSS tests in parallel

[HCastano]

As mentioned in #1032, the runtime of our tests is now pushing an hour. This PR changes
how our tests are setup in order to allow tests to run in parallel instead of serially.

For example, now the following command runs in parallel:

cargo test -p entropy-tss --release -- signature_request_with_derived_account_works test_signature_requests_fail_on_different_conditions --nocapture

test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 32 filtered out; finished in 139.16s

vs. running this on master

test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 30 filtered out; finished in 240.54s

I'll add more details here once it's out of a draft state.