Update aocsam.c: fix safeFSWriteSize arg type (#540)

The goal is to achieve consistent coding with https://github.com/cloudberrydb/cloudberrydb/blob/main/src/backend/access/aocs/aocsam.c#L174

Problem tracks down to commit 6b0e52b
No behavior change is expected, just a nit-pick

src/backend/access/aocs/aocsam.c

@@ -263,7 +263,7 @@ open_ds_read(Relation rel, DatumStreamRead **ds, TupleDesc relationTupleDesc,
 		ds[attno] = create_datumstreamread(ct,
 										   clvl,
 										   checksum,
-										    /* safeFSWriteSize */ false,	/* UNDONE:Need to wire
+										    /* safeFSWriteSize */ 0,	/* UNDONE:Need to wire
 																			 * down pg_appendonly
 																			 * column */
 										   blksz,
@@ -1561,7 +1561,7 @@ aocs_fetch_init(Relation relation,
 				create_datumstreamread(ct,
 									   clvl,
 									   checksum,
-									    /* safeFSWriteSize */ false,	/* UNDONE:Need to wire
+									    /* safeFSWriteSize */ 0,	/* UNDONE:Need to wire
 																		 * down pg_appendonly
 																		 * column */
 									   blksz,