Update playwright config to use workers in the CI

[acouch]

Changes

On grants.gov we recently tested using workers in Github Actions: HHS/simpler-grants-gov#5615 . We've seen test times drop on average by half (~4 mins to ~2 mins).

This is an optimization that helps locally too and has been tested by a couple of devs.

[lorenyu]

Have you tried using nproc to set the workers to the number of processors rather than hardcoding? e.g. when running the playwright command doing something like:

npx playwright test --workers=$(nproc)

[lorenyu]

@doshitan what do you think of this optimization? should we just hardcode it for now? seems reasonable, i think most of our laptops have 8 cores, and a quick google seems to show that github actions runners have 4 cores, so i think hardcoding to 8 seems reasonable. or if we wanted to make it more elegant we can add something to e2e/run-e2e-test to check for the number of cores like:

if [[ "$OSTYPE" == "linux-gnu"* ]]; then
  CORES=$(nproc)
elif [[ "$OSTYPE" == "darwin"* ]]; then
  CORES=$(sysctl -n hw.ncpu)
else
  CORES=1 # Fallback to running without parallelization
fi

npx playwright test --config "${APP_NAME}/playwright.config.js" --workers=$CORES "$@"

[doshitan]

It looks like by default Playwright will allocate cpu count / 2 workers. So can we just drop the explicit workers config item and use the default? Possibly set it to "100%" in CI since that environment should be more of a uni-tasker/can dedicate all it's resources to the e2e tests?