"I will restrain myself from answering as it is not a deployment issue" and "I will refrain from answering as it is not a deployment issue" (note no "myself" in the second one) both mean pretty much the same thing: You want to answer it but you're not going to.
I'd say that "restrain myself" implies a stronger urge to answer, and is more humorous. It is not quite a figure of speech, but it could make the reader picture the writer pulling their struggling-to-type-something hand away from the keyboard or something similar to that, i.e., of being literally restrained, like a struggling mental patient or somesuch. "Refrain from," on the other hand, is dryer, and also has a mild implication that the writer might consider it beneath them to answer.
So, more or less the same thing, but with different, subtle implications.