Avoid cloning when simplifying expressions for Log, Power UDF

[tinfoil-knight]

Is your feature request related to a problem or challenge?

@alamb pointed this out while reviewing #9983

https://github.com/apache/arrow-datafusion/blob/ad0abe91752b8da327e97b09d8ca883c782f027d/datafusion/functions/src/math/log.rs#L179

It would be really nice to avoid this clone (I am working to reduce the number of times we need to clone Exprs during planning). see tinfoil-knight#1 for a suggestion

See #9983 (comment)

Describe the solution you'd like

Avoid using .clone() wherever possible

Describe alternatives you've considered

No response

Additional context

No response

[tinfoil-knight]

take

[alamb]

I polished up some code I had and put it up as #10086