btree prefixnode type bug

[shosseinimotlagh]

command line: bin/test_mem_btree --gtest_filter=*/0.RandomRemove

Error: HomeStore/src/tests/btree_helpers/btree_test_helper.hpp:161: Failure Expected equality of these values: removed Which is: false m_shadow_map.exists(*pk) Which is: true Removal of key 43770 status doesn't match with shadow

[xiaoxichen]

@shosseinimotlagh pls verify if this ticket still valid?