Reformat async code (#1383)

* Update formatter

Motivation:

We need to use a newer version of SwiftFormat on the async/await code.
First we should update main so that merging changes into the async
branch is cleaner.

Modifications:

- Update SwiftFormat
- Reformat

Result:

Our version of SwiftFormat is new enough to correctly handle async/await
code.

(cherry picked from commit 8ab0e3ba5945d63a0911cb38246ddeea06bfceee)

* Reformat async code

Motivation:

On 'main' we updated SwiftFormat to a version which knows about
language features introduced in 5.5 and formatted the code accordingly.
We need to do the same on the async branch.

Modifications:

- Remove rules to temporarily disable SwiftFormat (in place for
  compatibility reasons)
- Rerun the formatter

Result:

Formatter is happy.

scripts/format.sh

@@ -21,8 +21,8 @@ REPO="$HERE/.."
 SWIFTFORMAT_DIR="$HERE/.swiftformat-source"
 
 # Important: if this is changed then make sure to update the version
-# in .travis-install.sh as well!
-SWIFTFORMAT_VERSION=0.46.3
+# in the .github/workflows/ci.yaml as well!
+SWIFTFORMAT_VERSION=0.49.4
 
 # Clone SwiftFormat if we don't already have it.
 if [ ! -d "$SWIFTFORMAT_DIR" ]; then