Add match guard let chain drop order and scoping tests

[est31]

We have a bunch of tests for if let chain drop order, but those tests don't cover match guard chains to the same depth. This PR adds the following tests:

• match guard equivalents of the if let chains tests in the drop-order-comparisons.rs test, added by Add extensive set of drop order tests #133605.
• match guard equivalent of the mir_let_chains_drop_order.rs test, added by Rescope temp lifetime in if-let into IfElse with migration lint #107251
• match guard equivalent of temporary-early-drop.rs, added by Let chains tests #133093

The added tests all have variants for 2021 and 2024, showing that the behavior on both editions matches that of if let chains on 2024.

tracking issue: #51114

[rustbot]

r? @petrochenkov

rustbot has assigned @petrochenkov.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer