test: shorten Mooncake test suite (#980)

Author: gdalle

DifferentiationInterface/test/Back/Mooncake/test.jl

@@ -7,6 +7,8 @@ using Test
 using ExplicitImports
 check_no_implicit_imports(DifferentiationInterface)
 
+nomatrix(scens) = filter(s -> !(s.x isa AbstractMatrix) && !(s.y isa AbstractMatrix), scens)
+
 backends = [
     AutoMooncake(),
     AutoMooncakeForward(),
@@ -20,14 +22,21 @@ for backend in backends
 end
 
 test_differentiation(
-    backends,
+    backends[3:4],
     default_scenarios(;
         include_constantified = true, include_cachified = true, use_tuples = true
     );
     excluded = SECOND_ORDER,
     logging = LOGGING,
 );
 
+test_differentiation(
+    backends[1:2],
+    nomatrix(default_scenarios());
+    excluded = SECOND_ORDER,
+    logging = LOGGING,
+);
+
 EXCLUDED = @static if VERSION ≥ v"1.11-" && VERSION ≤ v"1.12-"
     # testing only :hessian on 1.11 due to an opaque closure bug.
     # this is potentially the same issue as discussed in
@@ -54,7 +63,7 @@ end
 
 test_differentiation(
     backends[3:4],
-    static_scenarios();
+    nomatrix(static_scenarios());
     logging = LOGGING,
     excluded = SECOND_ORDER
 )