mongodb-agent deprecated in favour of mongodb-agent-ubi

[PhoenixMage]

What did you do to encounter the bug?
Deploying a mongodb instance using the mongodb operator on arm64 hardware results in the pod failing due to no arm64 image of mongodb-agent. The new mongodb-agent-ubi has a arm64 build.

Per mongodb/mongodb-kubernetes-operator#1408 (comment) mongodb-agent was deprecated in chart version 0.8.3 but current chart still uses the default value as "mongodb-agent", these needs to be replaced with "mongodb-agent-ubi" which will use the multi architecture tag which supports arm64.

[github-actions]

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