perf(tests): remove redundant format! in ef-tests run_only

[prestoalvarez]

Description:

• Summary: Replace unnecessary string formatting with a direct literal in tests to avoid temporary allocation and improve readability.
• Change: In testing/ef-tests/tests/tests.rs, use stringify!($dir) instead of &format!("{}", stringify!($dir)).
• Rationale: Eliminates one allocation and simplifies the code.