Fix segfaults during Create/Update for ec_deployment.

[dimuon]

Fix segfaults during Create/Update for ec_deployment

• when elasticsearch attribute contains both strategy and snapshot_source;
• when elasticsearch defines snapshot with repository that doesn't contain reference.

Description

Related Issues

Closes: #715

Motivation and Context

How Has This Been Tested?

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (improves code quality but has no user-facing effect)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation

Readiness Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

[danielmitterdorfer]

I've tested my reproduction scenario mentioned in #715 with this change and it works fine now. Thanks for the super quick fix!

[tobio]

LGTM