sql: make the cache option on sequences be per-node by default

[fqazi]

Now that we have per-node sequence caching support has been added, we should consider changing the default so that the CREATE SEQUENCE sequence_name CACHE ... syntax defaults to per-node out of the box. This is better behaved and more desirable for most customers.

We should additionally consider adding an alias for a PER SESSION optional syntax, which would give the existing behaviour of using CREATE SEQUENCE sequence_name CACHE ....

How to get started

• Do the SQL Statement Code Lab that runs through an example of adding new syntax.
• Modify the appropriate sub-rule underneath create_sequence_stmt in pkg/sql/parser/sql.y.

Jira issue: CRDB-42587

Epic CRDB-49398