Skip tests 1975 & 1976 on redefine-stress

These tests use the invoke-polymorphic opcode that is not supported by
slicer, causing these tests to fail in that configuration.

Bug: 134162467
Bug: 37272822
Test: ./test.py --host --redefine-stress
Test: ./test.py --host
Change-Id: I3d0c5ddc1e8bf4d1de528aa3ae00ebb042af7af5
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 42126d8..dd23b95 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -442,7 +442,9 @@
             ".*method-handle.*",
             ".*varhandle.*",
             ".*var-handle.*",
-            "716-jli-jit-samples"
+            "716-jli-jit-samples",
+            "1975-hello-structural-transformation",
+            "1976-hello-structural-static-methods"
         ],
         "description": [
             "Tests for bytecodes introduced after DEX version 037 that are unsupported by",