Enable conditional put by default for S3

[ion-elgreco]

In delta-rs we inject the conditional_put config when we see an S3 store. Is there a reason why object-store still requires you to explicitly enable this?

cc @kylebarron

[tustvold]

I think this makes sense, we historically held off as the S3 support was partial and changing config defaults would be a breaking change.

As we're already preparing for the next release to be breaking, this makes sense to me to change