Leaking sensitive data on span attributes

[ar-sematell]

Hello,

I noticed that the default behavior of this library is to add the query vars to the span attribute.
I know there is the option to use WithoutQueryVariables.
I think this is an insecure approach, as by default it potentially leaks variables and secrets to the open telemetry.

The most secure approach would be to invert the logic to WithQueryVariables, making the developer aware that if he wants the query variables, he would need to use this option, instead of the opposite: the developer is not aware, and the query variables are there.

Thanks for your attention!