Fix data_receipt_creation_per_byte in runtime-params-estimator

[jancionear]

data_receipt_creation_per_byte used to generate a thousand 10 byte receipts and then another thousand of 100kB ones.
It expects all receipts to be processed within 2 blocks, but 1000 * 100kB = 100MB and bandwidth scheduler allows to send only 4.5MB per height, so with the scheduler enabled it takes ~25 blocks to send 100MB of receipts. Because of that the number of receipts was reduced from 1000 to 40. Now all of them are processed within the expected two blocks, but 40 receipts are processed too quickly to properly estimate the cost.

data_receipt_creation_per_byte should probably be rewritten to better estimate the cost of creating receipts.

Refs zulip conversation