Use an explicit source in program.test.ts

[philrz]

In contemplating #3218, @nwt remarked:

This ultimately traces back to the change we made to the HTTP API to ignore the pool name zui sends along side a query. That pool was treated as a default source if the query didn't include an explicit source. Without it, you get the null source. And with type checking against the null source instead of a pool, you get errors.

Therefore in this branch I've added explicit leading from test to the queries, which gets the tests to pass again with the newer SuperDB dependency.

[philrz]

@nwt has confirmed that my proposed change here is indeed just papering over an underlying problem. The test failure is believed to be an accureate reflection of features in the app (probably related to pins) that no longer work due to an API change, so at some point someone will do the work to fix the app. In the meantime, closing this PR without merging.