[dice] Adjust the output type of make_sample_bcc_and_cdis()

This is part of the project of merging the two existing dice
wrapper libraries into the library libdiced_open_dice to
improve maintainability.

Bug: 267575445
Test: m android.hardware.security.dice-service.non-secure-software
Test: atest VtsAidlDiceTargetTest VtsAidlDiceDemoteTargetTest
Change-Id: If9ee66a320775897342f53d58ee11405a8e70c6f