Keep the Process and Printer of an inherits_group of the Wrong Length

A project whose inherits_group did not have one entry per filament plus
the process and printer entries was loaded as if it had none. The CLI
then looked for system presets under the names of the user presets,
found none and refused to slice a project that slices on main.

The group is now read as before: the process first, the printer last
and the filaments in between, up to the filament count. A filament
without an entry counts as a system preset. A group with fewer than two
entries is still ignored. The warning stays.

tests/cli/test_cli_malformed_input.sh

@@ -3,7 +3,7 @@
 # orca-slicer binary. Each case lives inline in CLI::run(), so only the binary can reach it.
 #
 # - A project whose inherits_group does not have one entry per filament plus the process and
-#   printer entries is loaded as if it had none.
+#   printer entries still loads.
 # - --slice N --arrange 1 on a project without plate metadata slices plate N.
 # - An assemble list object with an empty filament list, or a negative filament id, is rejected
 #   as a config error.
@@ -155,7 +155,7 @@ run_presets export --slice 0 --export-3mf project.3mf "$WORK/cube.stl"
 expect_status export $CLI_SUCCESS
 [ -f "$WORK/export/project.3mf" ] || { echo "FAIL: project export failed"; tail -n 40 "$WORK/export/log"; exit 1; }
 
-echo "== an inherits_group of the wrong length is ignored"
+echo "== an inherits_group of the wrong length still loads"
 for group in '[]' '[""]' '["", "", "", "", ""]'; do
     tag="inherits_$("$PY" -c 'import json, sys; print(len(json.loads(sys.argv[1])))' "$group")"
     rewrite_3mf "$WORK/export/project.3mf" "$WORK/$tag.3mf" inherits "$group"