MERGE16_FIXME: Now the pgstat has not worked, so disable the report first

[chenjinbao1989]

src/backend/storage/file/fd.c: 1579

/* MERGE16_FIXME: Now the pgstat has not worked, so disable the report first */

src/backend/utils/activity/pgstat.c: 1304
/* MERGE16_FIXME: Now the pgstat has not worked, so disable the assert first */

[tuhaihe]

This issue has been fixed by #1820. If not, please re-open it.