AWS Timestream support upserts

### Use Case

some records are getting rejected due duplicate records, these new records match existing records in measure name, timestamp, and dimensions yet have a different measure value. For some custom metrics I need the ability for the records to get updated with new measure values.

### Expected behavior

records updated with new measure value without the RejectedRecordsException.

### Actual behavior

record is getting RejectedRecordsException and dropped from telegraf

### Additional info

_No response_

Begin by locating the AWS Timestream output entry point and its handling of RejectedRecordsException. Check the AWS-supported behavior for records matching on measure name, timestamp, and dimensions, then verify that a replacement measure value is retained without the record being dropped.

Written by the indexing model from the issue text.