Enable LegacyTLSEnforced in testing config

Enables LegacyTLSEnforced feature in the testing config, for the new
study name (to fix server side config errors). Previously
crrev.com/c/2056936 updated the feature flag but not the study name.

Change-Id: Ibf55717fe10c87f9ea264c2e8fcc9355c537abc1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2065407Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Christopher Thompson <cthomp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743182}

testing/variations/fieldtrial_testing_config.json

@@ -3135,7 +3135,7 @@
             ]
         }
     ],
-    "LegacyTLSDeprecation": [
+    "LegacyTLSDeprecation2": [
         {
             "platforms": [
                 "android",