Fix block connection ordering in a number of functional tests

Fix block connection ordering in a number of functional tests

Many functional tests rely on being able to call block_connected
arbitrarily, jumping back in time to confirm a transaction at a
specific height. Instead, this takes us one step towards having a
well-formed blockchain in the functional tests.

We also take this opportunity to reduce the number of blocks
connected during tests, requiring a number of constant tweaks in
various functional tests.

Co-authored-by: Valentine Wallace <vwallace@protonmail.com>
Co-authored-by: Matt Corallo <git@bluematt.me>