ya-runtime-vm offer-template may print trailing garbage

[kamirr]

Random bytes are sometimes appended to stdout after the valid json is printed, when the program shuts down.

Currently worked around in golemfactory/yagna#2769, to be reverted when the fundamental issue is addressed.

[scx1332]

Extra bytes appears once in 5-20 times depending on luck. For me it was 7 extra bytes with no apparent meaning.