Use TX IDs for Bitcoin Eventualities

They're a bit more binding, smaller, provided by the Rust bitcoin library,
sane, and we don't have to worry about malleability since all of our inputs are
SegWit.

tests/full-stack/src/tests/mint_and_burn.rs

@@ -35,7 +35,7 @@ async fn mint_and_burn_test() {
 
       // Helper to mine a block on each network
       async fn mine_blocks(
-        handles: &Vec<Handles>,
+        handles: &[Handles],
         ops: &DockerOperations,
         producer: &mut usize,
         count: usize,