Summary:
Upgrade of colocated tables was failing because
 1) The OID for the tablegroup for the table wasn't being properly restored.
 2) YB properties including the colocation ID weren't being dumped by ysql_dump.

Fix both issues, and add a test.
Jira: DB-14006

Test Plan:
Jenkins

  ./yb_build.sh release --cxx-test pg15_upgrade-test --gtest_filter Pg15UpgradeTest.ColocatedTables --with_tests

Reviewers: telgersma, fizaa

Reviewed By: telgersma

Subscribers: yql

Differential Revision: https://phorge.dev.yugabyte.com/D40260