Cleanup dead code

Problem/Motivation

• TempstoreCollectionNotFoundException is defined but never thrown anywhere — likely leftover/unfinished feature.
• Both TskService (3 methods) and TskAdminController::listTemporaryStorages() have a duplicate catch (\Exception $e) { … } catch (\Exception $e) { … } — the second block is unreachable dead code (not a bug causing failures, but worth cleanup; a test exercising the generic-exception path would reveal only the first block ever runs).