LeAclMananager: Rename canceled_connections

Somewhere in refactoring, canceled_connections stopped tracking
connections that were cancelled and started being used as a boolean
to signify if connections should be armed.  Make that obvious.

Bug: 234496601
Test: gd/cert/run LeAclManagerTest
Tag: #gd-refactor
Change-Id: Ia3d16cc0385da25e91890874c6a1e96e72197ba4