Summary:
This revision / commit is similar to D39068 / 71c640c7793432db3a36e9a7f6028513b314dfe3, but adapted for YB PG15.

### Background:
(See revision / commit D39068 / 71c640c7793432db3a36e9a7f6028513b314dfe3 for more details).
Backup/Restore presently fails for rewritten partitioned tables since rewrite is not performed on the parent (inherited behaviour from PG).
Moreover, PG15 no longer generates a relfilenode for parent partitioned tables. In Yugabyte, however, we create a DocDB table for the parent (see GH issue #6525).

### Solution:
Since some table metadata is stored in DocDB (namely, `yb_table_properties`), it is not trivial to skip creating DocDB storage for parent partitioned tables. Instead, this revision diverges from PG and generates a relfilenode (and relam) for YB backed parent partitioned tables. Similar to commit 71c640c7793432db3a36e9a7f6028513b314dfe3, it also makes appropriate changes to propagate table rewrite to the parent.
Jira: DB-13116

Test Plan:
./yb_build.sh release --cxx-test pg15_upgrade-test --gtest_filter Pg15UpgradeTest.PartitionedTableRewrite
./yb_build.sh --cxx-test pgwrapper_pg_ddl_atomicity-test --gtest_filter PgDdlAtomicityTest.TestPartitionedTableSchemaVerification
./yb_build.sh --cxx-test yb-backup-cross-feature-test --gtest-filter YBBackupTest.TestPartitionedTableRewrite

Reviewers: myang

Reviewed By: myang

Subscribers: ybase, yql

Differential Revision: https://phorge.dev.yugabyte.com/D40946