Remove Vue2-based widget (#6610)

* Remove Vue2-based widget

* move floatformat.js

* Delete docready.js

* Update widget.py

src/tests/e2e/conftest.py

@@ -89,8 +89,6 @@ def _widget_assets():
                 f'Start it with: npm run dev:widget'
             )
         yield
-    elif os.environ.get("PRETIX_WIDGET_VUE"):
-        yield  # Old widget, no build needed
     else:
         subprocess.check_call(['npm', 'run', 'build:widget'], cwd=PROJECT_ROOT)
         yield