fix: changes batch samples to 1000 CPU millis

[telpirion]

Description

Issues with other PRs (e.g. #4408 )

Documentation of these settings: https://cloud.google.com/go/docs/reference/cloud.google.com/go/batch/latest/apiv1/batchpb#cloud_google_com_go_batch_apiv1_batchpb_ComputeResource

Checklist

• [x] I have followed Contributing Guidelines from CONTRIBUTING.MD
• [x] Tests pass: go test -v ./.. (see Testing)
• [x] Code formatted: gofmt (see Formatting)
• [x] Vetting pass: go vet (see Formatting)
• [ ] These samples need a new API enabled in testing projects to pass (let us know which ones)
• [ ] These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• [ ] This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• [ ] This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• [ ] Please merge this PR for me once it is approved

[iennae]

wooh! excellent find @telpirion ! Thank you for the sleuthing skills!