bump executor
bump executor

[finishes #163769813](https://www.pivotaltracker.com/story/show/163769813)

Submodule src/code.cloudfoundry.org/executor 252325c7..2297aa9e:
  > Do not remove proxy config dir in initializer (again)

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release