Delete unnecessary #pragma warning disable

[jkotas]

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[jkotas]

@roji These #pragmas were added in #110872. I do not see why they are necessary.

[eiriktsarpalis]

In some cases Rider will emit warnings that are not issued by the compiler. Perhaps it's an instance of that?

[roji]

Yeah, I think these slipped into the commit by mistake, sorry - I no longer remember the specific reason they were needed (in any case, everything builds fine without them and LeftJoin doesn't require them either, so...)