Added alternative expression field in AWS CloudWatch scaler

[dekelev]

Added alternative expression field in AWS CloudWatch scaler.
Here's an example ScaledObject config:

awsRegion: us-east-1
expression: >-
  SELECT MIN(MessageCount) FROM "AWS/AmazonMQ" WHERE Broker =
  'production' and Queue = 'worker'
metricCollectionTime: '60'
metricName: WorkerMessageCount
metricStatPeriod: '60'
minMetricValue: '0'
namespace: AWS/AmazonMQ
targetMetricValue: '100'

In addition, AWS CloudWatch scaler was changed to use int64 instead of float64 for metric type, since HPA doesn't work with float numbers, integers only.

Checklist

• Commits are signed with Developer Certificate of Origin (DCO - learn more)
• Tests have been added
• A PR is opened to update our Helm chart (repo) (if applicable, ie. when deployment manifests are modified)
• A PR is opened to update the documentation on (repo) (if applicable) Added alternative expression field in AWS CloudWatch scaler keda-docs#755
• Changelog has been updated and is aligned with our changelog requirements

In addition to PR #2911
Fixes #2998

[JorTurFer]

/run-e2e aws-cloudwatch*
Update: You can check the progres here

[dekelev]

@JorTurFer Docs changes PR in v2.7:
kedacore/keda-docs#755

https://deploy-preview-755--keda.netlify.app/docs/2.7/scalers/aws-cloudwatch/

[dekelev]

/run-e2e aws-cloudwatch* Update: You can check the progres here

@JorTurFer Looks like it's failing on something unrelated to this PR, right? Maybe it's not working because the PR is out of sync with the main branch? It was forked about 2 weeks ago.

[JorTurFer]

LGTM!
Thanks for the contribution! ❤️
Only 2 things thing, could you update the changelog with the changes?
I have created an issue for tracking this,
so the line that you have to add is something like this:

• AWS CloudWatch: Add support to use expressions(#2998)

(Under the ### Improvements section)

Please, rebase also the latest changes into your branch, there are some changes needed for running e2e tests

[dekelev]

LGTM! Thanks for the contribution! ❤️ Only 2 things thing, could you update the changelog with the changes? I have created an issue for tracking this, so the line that you have to add is something like this:

• AWS CloudWatch: Add support to use expressions(#2998)

(Under the ### Improvements section)

Please, rebase also the latest changes into your branch, there are some changes needed for running e2e tests

Done

[JorTurFer]

/run-e2e aws-cloudwatch*
Update: You can check the progres here

[zroubalik]

Generally looking good! Great job. Just a comment on metric name.

[zroubalik]

LGTM

[zroubalik]

/run-e2e aws-cloudwatch*
Update: You can check the progres here

[JorTurFer]

LGTM!
❤️ ❤️ ❤️ ❤️