[DOCS] Fix the R test that still has DBI call

[jiayuasu]

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• Yes, I have read Contributor Rules and Contributor Development Guide

Is this PR related to a JIRA ticket?

• No, this is a documentation update. The PR name follows the format [DOCS] my subject.

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Did this PR include necessary documentation updates?

• No, this PR does not affect any public API so no need to change the docs.

[jiayuasu]

@yitao-li Dear Yitao, could you please help me remove the DBI call in the test? My PR didn't work for this...

[yitao-li]

Nice catch!

[yitao-li]

Uh just noticed the build failures... ok I'll take a look soon

[yitao-li]

need to fix test failure (should be simple, I think) -- looking into it now

[yitao-li]

@jiayuasu I think #731 should fix it.
The CI run for that PR was cancelled after some unrelated test failure though, but if I run my version of sdf_sql(...) %>% collect() locally, I do get the expected result, so, I think it should work.

EDIT: actually all R builds are passing now in that PR ✅