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
am: e9d8dfe716

Change-Id: Idcfdc14d3743ea8a37769ec0caf840f73bb26c26