[NI] Prioritize variables with trivial constraints over complex ones

Consider the following constraint system (from the test example):

Nothing? <: V1
F!! <: V2
Inv<V1> <: S
Inv<V2> <: S

Where V1, V2, S are type variables, and F has nullable upper bound.
Type variable fixation order should be: V2 -> V1 -> S, and the problem
was that previously after fixation of type variable V2 we were trying
to fix S (before V1), so we had the following constraints on S:
Inv<F!!> <: S
Inv<V1> <: S
=> S were fixed to Inv<F!!>

And after this V1 was fixed to F!! which is contradictory as Nothing?
is not a subtype of F!!.

 #KT-33033 Fixed

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -10341,6 +10341,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     runTest("compiler/testData/diagnostics/tests/inference/constraints/errorUpperBoundConstraint.kt");
                 }
 
+                @TestMetadata("fixTypeVariableWithNothingConstraintEarlierThanComplexVariable.kt")
+                public void testFixTypeVariableWithNothingConstraintEarlierThanComplexVariable() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/constraints/fixTypeVariableWithNothingConstraintEarlierThanComplexVariable.kt");
+                }
+
                 @TestMetadata("ignoreConstraintFromImplicitInNothing.kt")
                 public void testIgnoreConstraintFromImplicitInNothing() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/inference/constraints/ignoreConstraintFromImplicitInNothing.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -10336,6 +10336,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                     runTest("compiler/testData/diagnostics/tests/inference/constraints/errorUpperBoundConstraint.kt");
                 }
 
+                @TestMetadata("fixTypeVariableWithNothingConstraintEarlierThanComplexVariable.kt")
+                public void testFixTypeVariableWithNothingConstraintEarlierThanComplexVariable() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/constraints/fixTypeVariableWithNothingConstraintEarlierThanComplexVariable.kt");
+                }
+
                 @TestMetadata("ignoreConstraintFromImplicitInNothing.kt")
                 public void testIgnoreConstraintFromImplicitInNothing() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/inference/constraints/ignoreConstraintFromImplicitInNothing.kt");