clearLockTask for root tasks as well at removal

The check is a remnant from the merge of stacks and tasks. However it's
very much possible that a root task being locked at ToT so we shouldn't
exclude them from unlocking when they are being removed.

Bug: 191052371
Test: atest TaskTests
Change-Id: I8380f26c03e60d913c7813d753cd68a46a38001d