Merge #10088: Trivial: move several relay options into the relay help group

Summary:
0fb2887 Move several relay options into the Relay help group (Jameson Lopp)

Tree-SHA512: 31fdfd8c741adb6fe6806a28955f0fbbc9360b1d8c3d8a28684794822f1b3231fffab93357357d986b81a4532c9eeabb79e5ede9378ff3ad8930ceb6588d9eb6

Backport of Core PR10088
https://github.com/bitcoin/bitcoin/pull/10088/

Test Plan:

make check
./bitcoind -help

whitelistrelay and whitelistforcerelay should be with the other relay options.

Reviewers: deadalnix, jasonbcox, Fabien, markblundeberg, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: jasonbcox, O1 Bitcoin ABC, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D3382