Cloudwatch: Fix issue with field calculation transform not working properly with Cloudwatch data (#28761)

* Cloudwatch: Fix issue with reducer transform not working properly with Cloudwatch data

* Updated go sdk and updated code

* CloudWatch: Improve test

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>