remove codegen from travis file (#2768)

Codegen verification step is now being run by CircleCI, so it's no longer necessary to run it on Travis, especially since we recently got a `toomanyrequests: You have reached your pull rate limit.` docker error. We want to reduce unnecessary docker requests.

Author: algobarb

.travis.yml

@@ -31,11 +31,6 @@ jobs:
         - scripts/travis/build_test.sh
 
     - stage: build_pr
-      os: linux
-      name: Ubuntu AMD64 CodeGen Verification
-      script:
-        - scripts/travis/codegen_verification.sh
-    - # same stage, parallel job
       os: linux
       name: Ubuntu AMD64 Build
       script:
@@ -92,11 +87,6 @@ jobs:
          - $mingw64 scripts/travis/build_test.sh
 
     - stage: build_release
-      os: linux
-      name: Ubuntu AMD64 CodeGen Verification
-      script:
-        - scripts/travis/codegen_verification.sh
-    - # same stage, parallel job
       os: linux
       name: Ubuntu AMD64 Build
       script:
@@ -217,9 +207,6 @@ before_cache:
    esac
    docker save -o $HOME/docker_cache/images.tar $(docker images -a -q)
 
-#after_success:
-#  - scripts/travis/upload_coverage.sh || true
-
 addons:
   apt:
     packages: