chore: Put interpreter use of lambdas behind the flag ksql.lambdas.enabled

[AlanConfluent]

Description

Now throws an error if the use of lambdas in the interpreter is attempted without setting ksql.lambdas.enabled=true

Testing done

Added RQTT

Reviewer checklist

• [ ] Ensure docs are updated if necessary. (eg. if a user visible feature is being added or changed).
• [ ] Ensure relevant issues are linked (description should include text like "Fixes #")

[jnh5y]

@AlanConfluent do we still want this change?

If so, there may be some plans which need to be generated.

[cla-assistant[bot]]

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