Merge pull request #6961

fa41d4c [qt] Move GUI related HelpMessage() part downstream (MarcoFalke)
faf93f3 [trivial] Reuse translation and cleanup DEFAULT_* values (MarcoFalke)
3307bdb Bugfix: Omit wallet-related options from -help when wallet is not supported (Luke Dashjr)
b966aa8 Constrain constant values to a single location in code (Luke Dashjr)