fix(ci): fix terraform s3 backend SignatureDoesNotMatch error in dynamically generated backend config

- Add skip_s3_checksum = true and skip_metadata_api_check = true to s3 backend config
- Use endpoints = { s3 = ... } instead of deprecated endpoint parameter in terraform init

.github/workflows/deploy-ai-workspace-iac.yaml

@@ -154,6 +154,7 @@ jobs:
               skip_region_validation      = true
               skip_requesting_account_id  = true
               skip_metadata_api_check     = true
+              skip_s3_checksum            = true
               force_path_style            = true
             }
           }
@@ -175,7 +176,7 @@ jobs:
           set -euo pipefail
           if [ -n "${TF_STATE_BUCKET}" ]; then
             terraform init -input=false \
-              -backend-config="endpoint=${TF_STATE_ENDPOINT}" \
+              -backend-config="endpoints={s3=\"${TF_STATE_ENDPOINT}\"}" \
               -backend-config="bucket=${TF_STATE_BUCKET}" \
               -backend-config="key=ai-workspace/terraform.tfstate" \
               -backend-config="region=${TF_STATE_REGION:-us-east-1}"