Merge bitcoin/bitcoin#32049: contrib: Fix gen-bitcoin-conf.sh

a24419f contrib: Fix `gen-bitcoin-conf.sh`. (David Gumberg)

Pull request description:

  In #31118, the format of bitcoind's `--help` output changed slightly in a way that breaks `gen-bitcoin-conf.sh`, modify the script to accommodate the new format, by starting after the line that says "Options:" and stripping the `-help` options and descriptions from the script output.

  Before this PR, all options above `-help` were excluded from the example bitcoin.conf.

ACKs for top commit:
  mabu44:
    Tested ACK a24419f
  glozow:
    ACK a24419f
  rkrux:
    tACK a24419f
  BrandonOdiwuor:
    crACK a24419f

Tree-SHA512: 2ef697166d0b37b61ec1a20e357b91d611c932a0e453c4669f74ab69e6310ea1776dce09c1b77e82746072265763cb0c750e6df4c8b4a7d39068fc03f97b221b

Author: glozow

contrib/devtools/gen-bitcoin-conf.sh

@@ -50,7 +50,8 @@ EOF
 # adding newlines is a bit funky to ensure portability for BSD
 # see here for more details: https://stackoverflow.com/a/24575385
 ${BITCOIND} --help \
-    | sed '1,/Print this help message and exit/d' \
+    | sed '1,/Options:/d' \
+    | sed -E '/^[[:space:]]{2}-help/,/^[[:space:]]*$/d' \
     | sed -E 's/^[[:space:]]{2}\-/#/' \
     | sed -E 's/^[[:space:]]{7}/# /' \
     | sed -E '/[=[:space:]]/!s/#.*$/&=1/' \