AdvertiseBinder: Use 'manager' instead of implicit 'it'

As there are nested lambdas, using same 'it' in both lambdas
can be confusing to find out what 'it' refers in inner lambda.

This CL renames 'it' to 'manager' to remove ambiguity.

Bug: 358692626
Test: atest AdvertiseBinderTest
Flag: EXEMPT, mechanical refactor
Change-Id: I34f6e2aa2729f6ad1b72fe81cdfbe03cbc3eb115