[Impeller] Remove OOB access & unused nodiscard statements in tests (#36404)

https://dart.googlesource.com/external/github.com/flutter/engine/+/315d0c2051c5d0a91e0b402c598e1ff36461aa89
1 file changed
tree: e5d1b47c63f98cd69534f159eeac06da9b287830
  1. commits.json