revert: don't build using -Werror when using Clang

reverts:
- e43a9ea.

Author: kwvg

ci/test/00_setup_env_mac.sh

@@ -15,4 +15,3 @@ export RUN_UNIT_TESTS=false
 export RUN_FUNCTIONAL_TESTS=false
 export GOAL="all deploy"
 export BITCOIN_CONFIG="--with-gui --enable-reduce-exports --disable-miner --with-boost-process"
-export NO_WERROR=1

ci/test/00_setup_env_native_fuzz.sh

@@ -16,4 +16,3 @@ export RUN_FUNCTIONAL_TESTS=false
 export RUN_FUZZ_TESTS=true
 export GOAL="install"
 export BITCOIN_CONFIG="--enable-zmq --disable-ccache --enable-fuzz --with-sanitizers=fuzzer,address,undefined,integer CC='clang-18 -ftrivial-auto-var-init=pattern' CXX='clang++-18 -ftrivial-auto-var-init=pattern' --with-boost-process"
-export NO_WERROR=1

ci/test/00_setup_env_native_multiprocess.sh

@@ -17,4 +17,3 @@ export BITCOIN_CONFIG="--with-boost-process --enable-debug CC=clang-18 CXX=clang
 # Additional flags for RUN_TIDY
 export BITCOIN_CONFIG="${BITCOIN_CONFIG} --disable-hardening CFLAGS='-O0 -g0' CXXFLAGS='-O0 -g0 -Wno-error=documentation'"
 export BITCOIND=dash-node  # Used in functional tests
-export NO_WERROR=1

ci/test/00_setup_env_native_tsan.sh

@@ -15,4 +15,3 @@ export GOAL="install"
 export BITCOIN_CONFIG="--enable-zmq --with-sanitizers=thread CC=clang-18 CXX=clang++-18 CXXFLAGS='-g' --with-boost-process"
 export CPPFLAGS="-DARENA_DEBUG -DDEBUG_LOCKORDER -DDEBUG_LOCKCONTENTION"
 export PYZMQ=true
-export NO_WERROR=1

ci/test/00_setup_env_native_ubsan.sh

@@ -13,4 +13,3 @@ export DEP_OPTS="NO_UPNP=1 DEBUG=1"
 export GOAL="install"
 export BITCOIN_CONFIG="--enable-zmq --enable-reduce-exports --enable-crash-hooks --with-sanitizers=undefined CC=clang-18 CXX=clang++-18"
 export PYZMQ=true
-export NO_WERROR=1

ci/test/00_setup_env_native_valgrind.sh

@@ -12,4 +12,3 @@ export NO_DEPENDS=1
 export TEST_RUNNER_EXTRA="--exclude rpc_bind,feature_bind_extra --timeout-factor=4"  # Excluded for now, see https://github.com/bitcoin/bitcoin/issues/17765#issuecomment-602068547
 export GOAL="install"
 export BITCOIN_CONFIG="--enable-zmq --with-incompatible-bdb --with-gui=no CC=clang-18 CXX=clang++-18"  # TODO enable GUI
-export NO_WERROR=1