Summary:
Uncomment and move the statement in the following YB_TODO comment block to the originally intended location.
```
/*
* YB_TODO(Deepthi@yugabyte)
* Need to reintroduce the following code
* for PG13 which reimplement this function.
* root->yb_num_referenced_relations++;
*/
```
This statement was originally added to [inheritance_planner()](https://github.com/yugabyte/yugabyte-db/commit/658402eacc11854c4abc9d0a5241adc8c94a0183) by commit 658402eacc11854c4abc9d0a5241adc8c94a0183, then the corresponding line became less obvious in pg15 code base because the upstream commit: [pg 86dc90056dfdbd9d1b891718d2e5614e3e432f35](https://github.com/postgres/postgres/commit/86dc90056dfdbd9d1b891718d2e5614e3e432f35) removed inheritance_planner() and merged it into grouping_planner().
Jira: DB-15716
Test Plan: ./yb_build.sh release --scb --sj --java-test org.yb.pgsql.TestPgRegressPartitions#pruning
Reviewers: amartsinchyk
Reviewed By: amartsinchyk
Subscribers: mihnea, yql, smishra
Differential Revision: https://phorge.dev.yugabyte.com/D42595