Remove generated streaming pb and pom files.

[ashione]

Why are these changes needed?

There are some auto-generated streaming files, which are not removed. This PR removes them totally.

Related issue number

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[jovany-wang]

Could you check the .gitignore file? Maybe we should remove all streaming stuff from gitignore.

[ashione]

Could you check the .gitignore file? Maybe we should remove all streaming stuff from gitignore.

empty returns of git grep -i "streaming" .gitignore