Remove duplicate uriParts.size() > 0 check

Summary:
Partial backport of Core PR10898 (commit b5fb339)
https://github.com/bitcoin/bitcoin/pull/10898/commits/b5fb33943fd6222571d13f8247fc611ebe2ba8c6

Test Plan: ninja check

Reviewers: deadalnix, Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2623