Added TestPartitionOpener_group

Added TestPartitionOpener_group for test_partition_opener.cpp, as this
file shall be used by liblp_apis_fuzzer and liblp_test_defaults

Test: make TestPartitionOpener_group
Bug: 285829660

Change-Id: I01da0a6896409af99af9e89092f6e1e3760cf4c2
1 file changed