feat: support `multi_az_with_standby_enabled` for opensearch #55

Job	Run time
terraform-module / Readme	0s
terraform-module / CI / Labels Validate	2s
terraform-module / CI / bats	33s
terraform-module / CI / Format HCL	15s
terraform-module / CI / Find modules	2s
terraform-module / CI / Validate Codeowners (owners)	0s
terraform-module / CI / Validate Codeowners (syntax)	4s
terraform-module / CI / Lint (.)	17s
terraform-module / CI / Lint (./examples/basic)	13s
terraform-module / CI / Lint (./examples/complete)	20s
terraform-module / CI / Lint (./examples/docs)	11s
terraform-module / CI / Lint (./examples/non_vpc)	12s
terraform-module / CI / Lint (./examples/opensearch_basic)	13s
terraform-module / ci	1s
terraform-module / Release	0s
	2m 23s

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