Changelog: move entry for BytesBuilder to v2.10
Changelog: move entry for BytesBuilder to v2.10

Change-Id: I2969f8c089d087042b2aa681d2d8a61a8f956556
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/156101
Auto-Submit: Kevin Moore <1d6e7d10d051cf619c5282da3c28fd8d3e0a65a4@google.com>
Reviewed-by: Kevin Moore <1d6e7d10d051cf619c5282da3c28fd8d3e0a65a4@google.com>
Commit-Queue: Kevin Moore <1d6e7d10d051cf619c5282da3c28fd8d3e0a65a4@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk