[DocsUI M3] Set maxLines=2 for the snackbar

By default snackbar has maxLines=1 for >600dp screen width and
maxLines=2 for <600dp screen width, in order to show the full message,
this CL overrides maxLines=2 for all screen sizes.

Check the attached bug for the demo.

Bug: 433352372
Test: Set proper font/display size and inspect manually
Flag: com.android.documentsui.flags.use_material3
Change-Id: If4daa8553a0a8f926280330c8103d228e7f1feea