Fix non-dismissible resumption players.

Ensure resumption players created when a non-dismissible notification
is cancelled force the 'isClearable' flag to true. This fixes a bug
where a resumption player is non-dismissable.

Test: manual - Finish item in Pocket Casts, attempt long-press dismiss.
Bug: 169271494
Change-Id: I186f9ee6fc228ad5bd1d49970fb44709783b74dc
Merged-In: I186f9ee6fc228ad5bd1d49970fb44709783b74dc
(cherry picked from commit 656e9864)