Fix stack manager coverity issue - not free after bt on/off

[Root Cause]
When BT on, will do btif_dm_init(), which do save uid_set;
But when BT off, not destory uid_set.

[Solution]
Add btif_dm_cleanup to destory uid_set when BT off.

Bug: 301369984
Test: atest net_test_btif pass

Change-Id: Ide030e58e23a2802e9e2fbb50433c7376dc7dc61