AWS spot failure - custom error message

We recently set the default for aws.batch.maxSpotAttempts to 0 in https://github.com/nextflow-io/nextflow/pull/5215 to avoid unexpected costs in cloud.

This is good, but it means we go back to the state we had before this feature was implemented, which is people's Nextflow pipeline runs crashing with the extremely unhelpful message that AWS returns. From memory this has no mention spot reclamation or anything, and is not at all intuitive for new users.

In order for aws.batch.maxSpotAttempts to work, I assume that Nextflow must be capturing these spot reclamation errors already. Even if we're not retrying, can we use that opportunity to print a more helpful error message to the Nextflow log explaining what has happened, and pointing to the maxSpotAttempts config option so that the user knows how to resolve it?

Start by tracing the AWS Batch handling associated with the aws.batch.maxSpotAttempts configuration option and determine where spot reclamation errors are captured. Confirm the current AWS error reaches the Nextflow log, then make the completed behavior a helpful message explaining spot reclamation and pointing users to maxSpotAttempts for resolution.