Fix |excludedDeskId| filter in removeActiveTask()

Fixes the filtering used to exclude a desk from the desks to remove a
task from that was mistakenly using |displayId| instead of |deskId|.

Flag: com.android.window.flags.enable_multiple_desktops_backend
Bug: 389960283
Test: atest WMShellUnitTests
Change-Id: I821a400a1ee070678ecb6afc6586bd86a0c24c38