Strip resources held by ResolverRankerService CB

ayepin@ already fixed this in IntentResolver as part of ag/26445398;
this CL just ports the relevant parts of that fix back to framework
Resolver. aosp/3737309 indicates that the unnecessarily-retained
resources were responsible for application footprints growing to
as much as 500MB.

Bug: 328084479
Test: ResolverActivityTest
Flag: EXEMPT bug fix
Change-Id: I21654b4989992659f26ab93a2ba54691f03aa857