refactor: simplify helper script

further discussion is needed on how exactly we will pass
environment-specific information to the tests.

tests/playwright/run.sh

@@ -2,7 +2,5 @@
 
 set -e
 
-base_url="https://dev-benefits.calitp.org"
-
 # also uses arguments from pytest.ini
-pytest --base-url $base_url
+pytest