Stop docker containers if E2E test fail

[josecelano]

Parent: #384

When E2E tests fail here, containers are not stopped.

# Run E2E tests with shared app instance
TORRUST_IDX_BACK_E2E_SHARED=true cargo test || exit 1

# Stop E2E testing environment
./docker/bin/e2e-env-down.sh

Instead of exiting immediately, we could call a function to run ./docker/bin/e2e-env-down.sh before exiting.