nix-testing -> daemon-trust-override

And only enable in the tests that need it. This makes it less of a
sledgehammer.

tests/build-remote-trustless-should-fail-0.sh

@@ -1,5 +1,9 @@
 source common.sh
 
+enableFeatures "daemon-trust-override"
+
+restartDaemon
+
 [[ $busybox =~ busybox ]] || skipTest "no busybox"
 
 unset NIX_STORE_DIR

tests/build-remote-trustless-should-pass-2.sh

@@ -1,5 +1,9 @@
 source common.sh
 
+enableFeatures "daemon-trust-override"
+
+restartDaemon
+
 # Remote doesn't trust us
 file=build-hook.nix
 prog=$(readlink -e ./nix-daemon-untrusting.sh)

tests/build-remote-trustless-should-pass-3.sh

@@ -1,5 +1,9 @@
 source common.sh
 
+enableFeatures "daemon-trust-override"
+
+restartDaemon
+
 # Remote doesn't trusts us, but this is fine because we are only
 # building (fixed) CA derivations.
 file=build-hook-ca-fixed.nix

tests/init.sh

@@ -20,7 +20,7 @@ cat > "$NIX_CONF_DIR"/nix.conf <<EOF
 build-users-group =
 keep-derivations = false
 sandbox = false
-experimental-features = nix-command flakes nix-testing
+experimental-features = nix-command flakes
 gc-reserved-space = 0
 substituters =
 flake-registry = $TEST_ROOT/registry.json