travis: transition from docker auto builds to manual pushes

.travis.yml

@@ -41,7 +41,7 @@ jobs:
       before_install:
         - export DOCKER_CLI_EXPERIMENTAL=enabled
       script:
-        - go run build/ci.go docker -image -manifest amd64,arm64 -upload karalabe/geth-docker-test
+        - go run build/ci.go docker -image -manifest amd64,arm64 -upload ethereum/client-go
 
     - stage: build
       if: type = push
@@ -58,7 +58,7 @@ jobs:
       before_install:
         - export DOCKER_CLI_EXPERIMENTAL=enabled
       script:
-        - go run build/ci.go docker -image -manifest amd64,arm64 -upload karalabe/geth-docker-test
+        - go run build/ci.go docker -image -manifest amd64,arm64 -upload ethereum/client-go
 
     # This builder does the Ubuntu PPA upload
     - stage: build