[Do not merge] Check that CI test failures show backtraces

[daira]

This is pacu/feature/transparent-balance from #1570, at a commit known to have a test failure, with #1603 cherry-picked onto it.

[daira]

Here are the backtraces for the expected failure.

From CI:

---- wallet::transparent::tests::transparent_balance_spendability stdout ----
thread 'wallet::transparent::tests::transparent_balance_spendability' panicked at /home/runner/work/librustzcash/librustzcash/zcash_client_backend/src/data_api/testing/transparent.rs:56:5:
assertion `left == right` failed
  left: Some(Zatoshis(100000))
 right: Some(Zatoshis(0))
stack backtrace:
   0: rust_begin_unwind
             at /rustc/aedd173a2c086e558c2b66d3743b344f977621a7/library/std/src/panicking.rs:647:5
   1: core::panicking::panic_fmt
             at /rustc/aedd173a2c086e558c2b66d3743b344f977621a7/library/core/src/panicking.rs:72:14
   2: core::panicking::assert_failed_inner
             at /rustc/aedd173a2c086e558c2b66d3743b344f977621a7/library/core/src/panicking.rs:342:17
   3: core::panicking::assert_failed
             at /rustc/aedd173a2c086e558c2b66d3743b344f977621a7/library/core/src/panicking.rs:297:5
   4: zcash_client_backend::data_api::testing::transparent::check_balance
   5: zcash_client_backend::data_api::testing::transparent::transparent_balance_spendability
             at /home/runner/work/librustzcash/librustzcash/zcash_client_backend/src/data_api/testing/transparent.rs:361:5
   6: zcash_client_sqlite::wallet::transparent::tests::transparent_balance_spendability
             at ./src/wallet/transparent.rs:897:9
   7: zcash_client_sqlite::wallet::transparent::tests::transparent_balance_spendability::{{closure}}
             at ./src/wallet/transparent.rs:896:42
   8: core::ops::function::FnOnce::call_once
             at /rustc/aedd173a2c086e558c2b66d3743b344f977621a7/library/core/src/ops/function.rs:250:5
   9: core::ops::function::FnOnce::call_once
             at /rustc/aedd173a2c086e558c2b66d3743b344f977621a7/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Locally with RUST_BACKTRACE=1 cargo test gives the same result as CI, modulo paths.

Locally with RUST_BACKTRACE=1 cargo test --profile=dev gives essentially the same result except that we also have a line number in check_balance:

[...]
   4: zcash_client_backend::data_api::testing::transparent::check_balance
             at /media/ssd/home/daira/research/librustzcash/zcash_client_backend/src/data_api/testing/transparent.rs:56:5
   5: zcash_client_backend::data_api::testing::transparent::transparent_balance_spendability
             at /media/ssd/home/daira/research/librustzcash/zcash_client_backend/src/data_api/testing/transparent.rs:361:5
[...]

Obtaining nearly the same stack trace as with full debug info, and with an overall improvement in build+test time, seems like a good deal to me.