Undeprecate X-Frame-Options (#25663)

The spec no longer uses the wording "legacy".

Author: lukewarlow

http/headers/X-Frame-Options.json

@@ -36,7 +36,7 @@
           "status": {
             "experimental": false,
             "standard_track": true,
-            "deprecated": true
+            "deprecated": false
           }
         },
         "ALLOW-FROM": {
@@ -113,7 +113,7 @@
             "status": {
               "experimental": false,
               "standard_track": true,
-              "deprecated": true
+              "deprecated": false
             }
           }
         }