Dead code removal: remove no longer used implementations of send and sendBatch

[KennethRuan]

Summary

Dead code removal! In queue.h, there is no longer any reference to send and sendBatch, both methods were replaced with alternative versions (sendWithResponse and sendBatchWithResponse) that return responses from the upstream Queues codebase rather than void.

Note: The new functions are now renamed to send and sendBatch after the dead code implementations were removed.

Testing

• bazel test //src/workerd/api/tests:queue-test@ //src/workerd/api/tests:queue-metrics-test@ //src/workerd/api/tests:queue-metadata-test@ //src/workerd/api/tests:queue-metrics-sentinel-test@ //src/workerd/api/tests:queue-producer-metadata-test@
• bazel test //src/workerd/api/tests:queue-test@all-compat-flags //src/workerd/api/tests:queue-metrics-test@all-compat-flags //src/workerd/api/tests:queue-metadata-test@all-compat-flags //src/workerd/api/tests:queue-metrics-sentinel-test@all-compat-flags //src/workerd/api/tests:queue-producer-metadata-test@all-compat-flags

[sdnts]

Looks good to me!