delete no-longer-used custom sdkpage template. depends on https://googleplex-android-review.git.corp.google.com/#/c/1389393/ am: 42859fae46 am: 618756ab95 am: 6deecc4c35
am: 9dbf2bb569

Change-Id: I09cff677cefadcec5caa399110fff884b446059c