Initiate anr_data_ for dumpstate limited only mode

When running in LimitedOnly mode, `anr_data_` was empty. Hence no ANR
traces were uploaded in the feedback reports.

Test reports uploaded:
http://listnr/product/208/report/91736461072
http://listnr/product/208/report/91736451197

Bug: 298145042
Test: Submit test reports to Listnr and verify the VM TRACES AT LAST ANR
session exist

Change-Id: I53981a73bfdb15e76007eb81567fe0fb5d00ee02