Failover for Citus doesn't support pg_dist_poolinfo (connection pooling)

We're testing out the newly added support in pg_auto_failover for a Citus formation. In our Citus formation, we use `pg_dist_poolinfo` alongside `pg_dist_node` so that the internal connections between Citus nodes are made through a connection pooler (pgbouncer). It does not appear that pg_auto_failover supports `pg_dist_poolinfo` though. In our testing, when pg_auto_failover triggers a failover, it makes the appropriate change to `pg_dist_node`, but not to `pg_dist_poolinfo`.

Before failover:
```
ourdb=# select * from pg_dist_node order by nodeid;
nodeid | groupid | nodename | nodeport | noderack | hasmetadata | isactive | noderole | nodecluster | metadatasynced | shouldhaveshards
--------+---------+-------------------+----------+----------+-------------+----------+----------+-------------+----------------+------------------
1 | 1 | citus-01-a.stg | 5432 | default | t | t | primary | default | t | t
2 | 2 | citus-02-a.stg | 5432 | default | t | t | primary | default | t | t
3 | 0 | citus-coord-a.stg | 5432 | default | t | t | primary | default | t | f
(3 rows)

ourdb=# select * from pg_dist_poolinfo order by nodeid;
nodeid | poolinfo
--------+-------------------------------------------------
1 | host=citus-01-a.stg port=6432 dbname=ourdb
2 | host=citus-02-a.stg port=6432 dbname=ourdb
3 | host=citus-coord-a.stg port=6432 dbname=ourdb
(3 rows)
```

After failover of `citus-02-a` to `citus-02-b`:

```

ourdb=# select * from pg_dist_node order by nodeid;
nodeid | groupid | nodename | nodeport | noderack | hasmetadata | isactive | noderole | nodecluster | metadatasynced | shouldhaveshards
--------+---------+-------------------+----------+----------+-------------+----------+----------+-------------+----------------+------------------
1 | 1 | citus-01-a.stg | 5432 | default | t | t | primary | default | t | t
2 | 2 | citus-02-b.stg | 5432 | default | t | t | primary | default | t | t
3 | 0 | citus-coord-a.stg | 5432 | default | t | t | primary | default | t | f
(3 rows)

ourdb=# select * from pg_dist_poolinfo order by nodeid;
nodeid | poolinfo
--------+-------------------------------------------------
1 | host=citus-01-a.stg port=6432 dbname=ourdb
2 | host=citus-02-a.stg port=6432 dbname=ourdb
3 | host=citus-coord-a.stg port=6432 dbname=ourdb
(3 rows)
```

So, after failover, `citus-02-b` has taken the place of `citus-02-a` in `pg_dist_node`, but the corresponding row in `pg_dist_poolinfo` still points at `citus-02-a`. This renders the cluster inoperable.