chore(camel-test-infra-milvus): upgrade milvus.container to v2.6.6

[github-actions]

This PR updates the milvus.container container image to version v2.6.6.

Update Details

• Property: milvus.container
• Image: mirror.gcr.io/milvusdb/milvus
• File: /home/runner/work/camel/camel/test-infra/camel-test-infra-milvus/src/main/resources/org/apache/camel/test/infra/milvus/services/container.properties
• Old version: v2.5.11
• New version: v2.6.6

Verification

Please verify:

• Container image version is compatible with existing tests
• No breaking changes in the updated version
• Tests pass with the new version

Run the following to verify:

mvn clean verify -pl camel-test-infra-milvus

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This PR was automatically created by the Container Version Upgrade workflow.