Velero/Restic integration is susceptible to a race condition when Velero checks Restic "summary"

Issue

• We observed a run of Restic reporting a failure even though it was successful.
• The issue is that the data Velero parsed to get Restic's status was malformed from what looks to be a race condition writing to stdout.
• Velero was parsing a JSON blob similar to below:

{\"message_type\":\"sumtus\",\"seconds_elapsed\":43,\"percent_done\":1,\"total_files\":3460,\"files_done\":3460,\"total_bytes\":242398842,\"bytes_done\":242398842}\n

• Velero was looking for the word 'summary', instead the key in the blob was 'sumtus', assume a combination of "summary" and "status" and some pieces writing over each other.