Support removing all placement rules from a {table,partition,database}

[djshow832]

Development Task

Background

It's a part of project "Placement rules in SQL". It should accomplished after adding placement rules (#18200).

Removing placement rules for a table is implemented with:

ALTER DATABASE test [DEFAULT] PLACEMENT POLICY SET DEFAULT; -- standard syntax for ALTER DATABASE
ALTER DATABASE test [DEFAULT] PLACEMENT POLICY=default; -- alternative
ALTER TABLE t1 PLACEMENT POLICY=default;
ALTER TABLE t1 PARTITION partition_name PLACEMENT POLICY=default;

All placement rules defined on the table will be removed.

Tasks

• Support syntax in the parser
• Validate the SQL
• Notify PD to drop the placement rules

[sylzd]

/assign