Mark dumpdb and loaddb as deprecated.

Review Request #11592 — Created April 12, 2021 and submitted — Latest diff uploaded

Review Board

The dumpdb and loaddb commands have reached their limit in terms of
usefulness. While they could be helpful in limited situations, they
won't be compatible with Review Board 4.0+, primarily because the data
generated (by Django) won't at all be compatible with Django > 1.6.

In practice, there have always been issues with dumping data on one
version of Review Board and loading it on another, due to the
possibilities of database schema changes, which these tools cannot
address. Because of this, along with other hard-to-solve problems that
manifested under Review Board 4.0, we're going to be removing these
tools entirely, suggesting that people instead use the database's native
tools for moving databases.

Power Pack will soon be providing a more future-proof way of handling
database dumps, so we have a successor coming soon.

This change marks these tools as deprecated in the help output, and
explains the situation when running either tool.

Ran both commands, ensuring they work and display the appropriate notice.