Remove GotVersion()

Summary:
GotVersion() is horribly named and does not actually described what it
is doing (rather, it describes when it is called which is confusing and
useless). Additionally, it only has one call site remaining, so replacing it
inline would make the code easier to read.

Test Plan:

ninja

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, jasonbcox

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D5344