Replaced manual login and context loading across tests with Playwright's `test.use` configuration for user authentication. This simplifies test setup, improves readability, and reduces repetition.
For #6362
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6400
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Julian Schlarb <julian.schlarb@denktmit.de>
Co-committed-by: Julian Schlarb <julian.schlarb@denktmit.de>