Added experiment to execute client for user_groups

[Gabefire]

Description

• See the attached issue. The user is complaining about the endpoint that is used for user groups.
• TLDR: client.execute has an experiment parameter outside the client. Setting the enable_experiment parameter swaps the endpoint used in the SDK from "/graphql" to "/_gql." From my understanding of these different URLs, they don't mean much anymore. The user must have some SSL certificate verification check in his local environment that monitors if the experiment is turned on for the correct URL because his other issue he has submitted is similar.
• I just changed what is passed to the experiment parameter inside user_groups for consistency. I thought about slightly modifying client.execute to override the experiment parameter if enabled_experiment is its own, but not sure of downstream effects or the exact reason the two experiment places are different (maybe some legacy feature)

[Gabefire]

#1808