fix: remove duplicate invalidBatchCount increment in batch decoder

[oooLowNeoNooo]

Fix double counting of invalid batches in batch decoder fetch logic

The invalidBatchCount was being incremented twice for transactions with
invalid senders:

1. First increment on line 103 when detecting invalid sender
2. Second increment on line 164 in the final validation check

This caused transactions with invalid senders to be counted twice in the
invalid batch statistics, leading to incorrect reporting of batch
validation results.

[opgitgovernance]

This pr has been automatically marked as stale and will be closed in 5 days if no updates