feat(ci): RUST_BACKTRACE=1 for all tests

[shekhirin]

It will make flaky tests easier to debug:

--- TRY 2 STDERR:        reth-node-core node_config::tests::optimism_post_canyon_withdrawals_valid ---
thread 'tokio-runtime-worker' panicked at /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bytes-1.5.0/src/buf/buf_impl.rs:289:9:
assertion failed: self.remaining() >= 1
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
2024-01-30T10:58:03.134574Z ERROR reth_tasks: Critical task `consensus engine` panicked: `assertion failed: self.remaining() >= 1`
thread 'node_config::tests::optimism_post_canyon_withdrawals_valid' panicked at crates/node-core/src/node_config.rs:1786:13:
post-canyon engine call with withdrawals should succeed: Call(ErrorObject { code: InternalError, message: "Server error", data: Some(RawValue({"err":"beacon consensus engine task stopped"})) })