profcollect: Copy report file to BetterBug's internal storage

BetterBug cannot directly access profcollectd's cache dir, let
profcollectd copy the report to BB's internal storage instead, as it has
higher privilege.

Test: manual
Bug: 79161490
Bug: 183487233
Change-Id: If86a00ab9fe9ed3c1418ca3ffe225b19ad4711b4