Bug 1371014 - do not run Talos on nightly builds. r=rwood

We are currently running talos on nightly builds and the results are being posted as 'opt'.  There is no value in tracking nightly builds as we have larger sample sizes of 'opt' and 'pgo' data.

In addition we run AWSY on nightly and devedition, as this is a performance test, we need to run this on builds where we can get useful data just like talos.

MozReview-Commit-ID: JyPGJ3p8h4c

taskcluster/ci/test/test-platforms.yml

@@ -58,8 +58,6 @@ linux64-nightly/opt:
         - web-platform-tests
         - opt-only-tests
         - desktop-screenshot-capture
-        - talos
-        - awsy
         - headless
 linux64-devedition/opt:
     build-platform: linux64-devedition-nightly/opt
@@ -68,7 +66,6 @@ linux64-devedition/opt:
         - web-platform-tests
         - opt-only-tests
         - desktop-screenshot-capture
-        - awsy
         - headless
 
 # TODO: use 'pgo' and 'asan' labels here, instead of -pgo/opt