Update references to sdkextensions cts

Renamed to SdkExtensionsTestCases.

Bug: 137191822
Test: atest --test-mapping frameworks/base/apex/sdkextensions
Change-Id: Idb544b2df013ccb88f6c4f0d590206e73661357a
diff --git a/apex/sdkextensions/TEST_MAPPING b/apex/sdkextensions/TEST_MAPPING
index 7e77623..4e18833 100644
--- a/apex/sdkextensions/TEST_MAPPING
+++ b/apex/sdkextensions/TEST_MAPPING
@@ -1,7 +1,7 @@
 {
   "presubmit": [
     {
-      "name": "CtsSdkExtTestCases"
+      "name": "CtsSdkExtensionsTestCases"
     },
     {
       "name": "apiextensions_e2e_tests"