Add Gitlab::Redis::TraceChunks Redis instance

What does this MR do?

gitlab-com/gl-infra/scalability#1058 (closed)

In gitlab-com/gl-infra&462 (closed) we are working towards using a dedicated Redis instance for CI trace chunk storage. This MR adds a new instance Gitlab::Redis::TraceChunks. There is no code yet that refers to this new instance; that will be added later when we work on gitlab-com/gl-infra/scalability#1095 (closed).

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Does this MR meet the acceptance criteria?

Conformity

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• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
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Availability and Testing

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Security

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• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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