Always validate hashes when provided

[nsoranzo]

Currently when uploading datasets with associated hashes, this were only validated if validate_hashes=True was also passed in the request.

This commit drops validate_hashes completely and always validates hashes when they were provided.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[nsoranzo]

Integration test failure unrelated.

[bgruening]

Makes sense to me!

[mvdbeek]

@jmchilton are ok with this ?

[jmchilton]

I'm +0 on it, feel free to merge.

[nsoranzo]

Thanks @jmchilton !