fix: Change the way to get default KMS for EBS

[sebastianczech]

Description

PR fixes the way to get default KMS for EBS in all examples.

Motivation and Context

#98

How Has This Been Tested?

It was tested locally by executing terraform plan . If some of the owner can apply all examples using ChatOps, I would be grateful.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes if appropriate.
• All new and existing tests passed.

[michalbil]

/apply paths="examples/centralized_design examples/centralized_design_autoscale examples/combined_design examples/combined_design_autoscale examples/isolated_design examples/isolated_design_autoscale examples/panorama_standalone examples/vmseries_standalone examples/cloudngfw_combined_design examples/cloudngfw_isolated_design"

Testing job ID: 12779108662
Job result: FAILURE

[migara]

@sebastianczech Thanks for the PR

[slawomir-kaczmarek]

Thank you Sebastian for the PR, the change is working fine as always ;) I just had to create a new PR where I left your change and made similar changes to VM-Series and Panorama modules on top of that, so I am closing this one.
#101