Inline the notifications_pinned_hun_in_shade flag

Fixes: 409629908
Bug: 385041854
Test: ensure that FSI HUNs are displayed correctly in the shade
       - open the shade
       - scroll up the stack
       - receive a HUN with FSI
Test: ensure that regular HUNs are displayed correctly in the shade
       - open the shade
       - scroll up the stack
       - receive a HUN (without FSI)
Flag: EXEMPT mechanical refactor
Change-Id: I4cfbb898ba359cdf48e3434b1553c57c92f0eae3