[BACKPORT 2024.1][#23777] yugabyted: update the gflags of pg parity t…

…o remove sized based fetching and add bitmap scans.

Summary:
Original commit: 3eb31b8 / D37748
Removed yb_fetch_row_limit=0, yb_fetch_size_limit=1MB and included yb_enable_bitmapscan=true.
Jira: DB-12683

Test Plan: Manual Tests

Reviewers: djiang

Reviewed By: djiang

Subscribers: yugabyted-dev

Differential Revision: https://phorge.dev.yugabyte.com/D37914

bin/yugabyted

@@ -381,9 +381,8 @@ PG_PARITY_FLAGS_DICT = {
 "ysql_pg_conf_csv": "yb_enable_base_scans_cost_model=true,"
                       "yb_enable_optimizer_statistics=true,"
                       "yb_bnl_batch_size=1024,"
-                      "yb_fetch_row_limit=0,"
-                      "yb_fetch_size_limit=1MB,"
-                      "yb_use_hash_splitting_by_default=false"
+                      "yb_use_hash_splitting_by_default=false,"
+                      "yb_enable_bitmapscan=true"
                     }
 
 # YugaWare configs. These have their own separate subdirectory to preserve our itest flow.