[block][prop test] split random_request_parse()
[block][prop test] split random_request_parse()

Move the lambda logic inside random_request_parse() to different method
for improved readability and better IDE parsing.

Signed-off-by: Serban Iorga <4cd75ae1c2f5ea126376f5daa1ce9f5f3016cb24@amazon.com>

firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker