Merge bitcoin/bitcoin#29669: ci: Drop --enable-c++20 option

64722e4 ci: Drop `--enable-c++20` option (Hennadii Stepanov)

Pull request description:

  This option has ceased to exist since bitcoin/bitcoin#28349.

ACKs for top commit:
  maflcko:
    ACK 64722e4

Tree-SHA512: bd392c331f775605615e1b236682269b83a1e6363a4d3f09c4d8d54495cf3d22973a921ebf6b8a9f813ba6c024d3324761f3291aaf7f473995f5eaa4c195bc43

Author: fanquake

ci/test/00_setup_env_native_asan.sh

@@ -20,7 +20,7 @@ export CONTAINER_NAME=ci_native_asan
 export PACKAGES="systemtap-sdt-dev clang-17 llvm-17 libclang-rt-17-dev python3-zmq qtbase5-dev qttools5-dev-tools libevent-dev libboost-dev libdb5.3++-dev libminiupnpc-dev libnatpmp-dev libzmq3-dev libqrencode-dev libsqlite3-dev ${BPFCC_PACKAGE}"
 export NO_DEPENDS=1
 export GOAL="install"
-export BITCOIN_CONFIG="--enable-c++20 --enable-usdt --enable-zmq --with-incompatible-bdb --with-gui=qt5 \
+export BITCOIN_CONFIG="--enable-usdt --enable-zmq --with-incompatible-bdb --with-gui=qt5 \
 CPPFLAGS='-DARENA_DEBUG -DDEBUG_LOCKORDER' \
 --with-sanitizers=address,float-divide-by-zero,integer,undefined \
 CC='clang-17 -ftrivial-auto-var-init=pattern' CXX='clang++-17 -ftrivial-auto-var-init=pattern'"