Avoid trying to upload to GCP if `0` files in batch

[bruno-garcia]

If a batch was started and finished with 0 files, don't bother trying to send data to GCP

SymbolCollector.Server.SymsorterBatchFinalizer
info
15:31:04.826
Symsorter processed: "0"
SymbolCollector.Server.SymsorterBatchFinalizer
info
15:31:04.826
Symsorter finished in 00:00:00.0025116 and logged last: "Sorted 0 debug files"
SymbolCollector.Server.SymsorterBatchFinalizer
info
15:31:04.825
Sorted 0 debug files
SymbolCollector.Server.SymsorterBatchFinalizer
info
15:31:04.825
Done.