Keep GTS tests in internal cf.

Bug: 300519349
Test: presubmit

Change-Id: I720285ddafc5493a172a0125bdbf31adadda2eba
diff --git a/native/webview/TEST_MAPPING b/native/webview/TEST_MAPPING
index c1bc6d7..07f4383 100644
--- a/native/webview/TEST_MAPPING
+++ b/native/webview/TEST_MAPPING
@@ -26,6 +26,7 @@
     },
     {
       "name": "GtsWebViewTestCases",
+      "keywords": ["internal"],
       "options": [
         {
           "exclude-annotation": "android.test.FlakyTest"
@@ -34,6 +35,7 @@
     },
     {
       "name": "GtsWebViewHostTestCases",
+      "keywords": ["internal"],
       "options": [
         {
           "exclude-annotation": "android.test.FlakyTest"