[NI] Don't skip constraints with projections during variable fixation

Those constraints are only restored for variable fixation stage because of the
influence on pefrormance.

^KT-37650 Fixed
^KT-37380 Fixed

compiler/fir/analysis-tests/tests/org/jetbrains/kotlin/fir/FirOldFrontendDiagnosticsTestGenerated.java

@@ -11473,6 +11473,11 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirOldFronte
                 runTest("compiler/testData/diagnostics/tests/inference/regressions/kt37043_2.kt");
             }
 
+            @TestMetadata("kt37650.kt")
+            public void testKt37650() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/regressions/kt37650.kt");
+            }
+
             @TestMetadata("kt4420.kt")
             public void testKt4420() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/inference/regressions/kt4420.kt");