MM-31064: Simplify indentation (#16565)

* MM-31064: Simplify indentation

Reduce indentation where possible.

```release-note
NONE
```

Command ran to verify:
golangci-lint run --disable-all --enable golint --max-issues-per-linter=10000 --max-same-issues=100000 ./... | grep "block ends with a return state"

https://mattermost.atlassian.net/browse/MM-31064

* incorporate review comments

* enable golint for outdent rule

* fix remaining issues

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

utils/testutils/testutils.go

@@ -28,9 +28,8 @@ func ReadTestFile(name string) ([]byte, error) {
 	data := &bytes.Buffer{}
 	if _, err := io.Copy(data, file); err != nil {
 		return nil, err
-	} else {
-		return data.Bytes(), nil
 	}
+	return data.Bytes(), nil
 }
 
 // GetInterface returns the best match of an interface that might be listening on a given port.