next.js

005db430 - chore(CI): Use `TEST_CONCURRENCY` by default in `run-tests.js` (#78731)

chore(CI): Use `TEST_CONCURRENCY` by default in `run-tests.js` (#78731) It seems too easy to accidentally not pass through `TEST_CONCURRENCY` in `build_and_test.yml`, so IMO `run-tests.js` should use it by default, still allowing overriding with `-c` or `--concurrency`. I tested by spot-checking CI jobs for log lines like this: ``` Running tests with concurrency: 4 in test mode undefined ``` or ``` Running tests with concurrency: 1 in test mode undefined ```