travis: use travis_wait for both install and build (#20309)

.travis.yml

@@ -47,7 +47,7 @@ jobs:
       dist: xenial
       go: 1.13.x
       script:
-        - go run build/ci.go install
+        - travis_wait 20 go run build/ci.go install
         - travis_wait 30 go run build/ci.go test -coverage $TEST_PACKAGES
 
     - stage: build