Cloud Dedicated write limit recommendations

This issue is for tracking outcomes and recommendations we can provide to help Cloud Dedicated customers scale or adjust their write workloads to fit their cluster.

Regarding Cloud Dedicated write limits...

After some digging, my understanding, which seems to be inline with the customer's request, is that
- Dedicated doesn't currently return `429`. In the same context
- `503` means Ingesters aren't available to handle the data.
- There is [ongoing work](https://influxdata.slack.com/archives/C07D4751ZFV/p1721689755810949) to address scaling and limiting of writes
- No "cluster-sized" limits or recommendations are provided to customers.

We can eventually incorporate the outcome/findings/guidance from that work to explain how writes and Ingestors are scaled and to make recommendations in the docs.
For now, I'm not sure we can say anything beyond "Try the request again."

No file, test, or documentation entry point is named. Review the ongoing scaling and limiting work referenced in the issue, then use its findings to define Cloud Dedicated write guidance and confirm what recommendations can be documented beyond retrying the request.

Written by the indexing model from the issue text.