[BEAM-4119] Update i/o testing documentation to use gradle

[lgajowy]

This is to update the io testing documentation with lately added Gradle commands. Due to the fact that there are no profiles in Gradle, some thing had to be done differently, hence some changes in the running instructions too.

CC: @melap @chamikaramj @swegner

[chamikaramj]

LGTM. Thanks.

[chamikaramj]

R: @melap can you take another look and merge ?

[melap]

retest this please

[melap]

Hi there @lgajowy , thanks for the PR! the content/ directory on the website is autogenerated from the files in the src/ directory after a merge, so your changes here would be overwritten. could you please move your changes into the associated file in the src/ directory (src/documentation/io/testing.md) and revert the content/ file? thanks!

[lgajowy]

@melap done - I guess I should have figured it out earlier. :) Could you take another look?

[melap]

staging link: http://apache-beam-website-pull-requests.storage.googleapis.com/425/documentation/io/testing/index.html

[melap]

This is great! just one very minor comment/question -- if you could check that out, and if so just fix/rebase and I (or someone else) will merge. thank you! 😄

[melap]

Should this one have -D like the other options?

[lgajowy]

True - same as logLevel in line 450. Corrected both.

[lgajowy]

@melap thanks! Corrected and rebased.

[melap]

Thanks!

[melap]

@asfgit merge

[asfgit]

Error: PR failed in verification; check the Jenkins job for more information.

[melap]

@asfgit merge

[asfgit]

Error: PR failed in verification; check the Jenkins job for more information.

[melap]

There's a problem with a link that is unrelated to this PR. I will try to merge again tomorrow.

[melap]

@asfgit merge

[asfgit]

Error: PR failed in verification; check the Jenkins job for more information.

[melap]

@asfgit merge