Refactor RemoteSpawn{Strategy,Runner}

- Make the RemoteSpawnRunner match RemoteSpawnStrategy functionality, including
  local fallback, remote caching, and execution. This is done so we can
  actually finish the migration to the SpawnRunner API, for which I've had a
  pending change for several months now.

- Never throw StatusRuntimeException from the GrpcRemoteCache or the
  GrpcExecutor. We almost never do, since the Retrier catches them implcitly,
  so a number of catch blocks were already unreachable. Carefully document
  the cases where we still need to handle it.

- RemoteSpawnStrategy / RemoteSpawnRunner no longer catch gRPC-specific
  exceptions; they should be able to handle any reasonable remote caching /
  execution implementation (except we don't have a common interface for
  GrpcRemoteExecutor yet), with no dependency on gRPC as such. Note that the
  RemoteSpawnStrategy class will actually go away after the SpawnRunner
  migration (eventually).

- However, ensure that we _are_ actually throwing CacheNotFoundException;
  the retrier implicitly catches that also, so we need to manually unwrap
  from RetryException.

- Don't call into the EventHandler from RemoteSpawnStrategy; instead, throw
  an exception with the message, and let the higher levels handle the
  reporting (we only allow this for exception + local fallback, for which
  there's no good reporting API right now).

PiperOrigin-RevId: 161195666

0 files changed, 0 insertions, 0 deletions