Clean up justfile and testing

[ludfjig]

First commit:

• Renames the just recipe for testing to test (instead of test-rust) and for building to build (instead of build-rust)
• Reorders the justfile after category: building, testing, linting, rust-examples, artifacts, benchmarks, fuzzing, flatbuffrers
• Modifies several crates' cargo.toml to set doctest=false, so that cargo test doesn't show noise (running 0 tests)
• Removes the need to set environment variables for certain rust examples/tests

Second commit:

• fixes a bug where the gdb test failed if the terminal size was too small (due to pagination).