Simplify patches and make them more robust

[mehrdadn]

Why are these changes needed?

Most of our patches have extraneous information and additional context that is unnecessary, confusing, or even outright wrong (such as file hashes that won't match, e.g. due to the order in which patches are applied).

Unnecessary context in particular can also result in extraneous conflicts when updating a library, and make it harder to understand what is going on.

Simplifying them to include only the relevant lines (instead of just the 3-line default) makes them easier to understand and maintain.

Note: when reviewing: I recommend split view when reviewing, rather than unified view, or the changes may be confusing. (You can switch by clicking the gear icon in the changes tab.)

Related issue number

#631

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://ray.readthedocs.io/en/latest/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failure rates at https://ray-travis-tracker.herokuapp.com/.

[AmplabJenkins]

Can one of the admins verify this patch?

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/19568/
Test FAILed.

[pcmoritz]

LGTM!