Reduce severity level of some message

Dependencies

• [2] SOB276BA Keep some statistics for the binary cache stores
• [3] ZM34T2NW Typo
• [4] GTUZLZRH Add an S3-backed binary cache store

Change contents

• replacement in src/hydra-queue-runner/s3-binary-cache-store.cc at line 138
  [3.4472]→[3.4472:4555](∅→∅)
  − printMsg(lvlError, format("uploaded ‘s3://%1%/%2%’ (%3% bytes) in %4% ms")
  [3.4472]

  [2.5160]
  + printMsg(lvlInfo, format("uploaded ‘s3://%1%/%2%’ (%3% bytes) in %4% ms")
• replacement in src/hydra-queue-runner/s3-binary-cache-store.cc at line 167
  [3.5230]→[3.0:85](∅→∅)
  − printMsg(lvlError, format("downloaded ‘s3://%1%/%2%’ (%3% bytes) in %4% ms")
  [3.5230]

  [2.5367]
  + printMsg(lvlInfo, format("downloaded ‘s3://%1%/%2%’ (%3% bytes) in %4% ms")