Update some tests to not return `Result<()>` and use unwrap() instead of `?`

With tests that return Result<()>, a failure can result in a non specific message like this:

thread 'test::integration_test_region' panicked at 'assertion failed: `(left == right)`
  left: `1`,
 right: `0`: the test returned a termination value with a non-zero status code (1) which indicates a failure', /rustc/65c55bf931a55e6b1e5ed14ad8623814a7386424/library/test/src/lib.rs:195:5

That may be fine for a simple test that only does one thing, but many crucible tests do a bunch
of stuff, include calling out to places that can fail. If we change these tests to .unwrap() instead
of ? and don't return Resutl<()> from the test, we can get more meaningful errors, like this:

thread 'test::integration_test_region' panicked at 'called `Result::unwrap()` on an `Err` value: Block size mismatch', integration_tests/src/lib.rs:232:66

Start in integration_tests/src/lib.rs, including the example location at line 232, and find tests that return Result<()> and propagate failures with ?. Replace the relevant test error propagation as described, then run the affected integration tests and confirm failures report the underlying error and location.