feat!: enable poll even when realTime flag is enabled

[ajinkyasurya]

• Real time service for on-prem solution is currently unstable and development is still in-progress.
• Requesting to enable poll even when useRealtime flag is enabled as failure to update environment is undesirable.
• I understand that I can externally pollEnvironment but I wanted to raise a PR and get an official review to save back and forth.

[rolodato]

This would be a breaking change, since it changes the behaviour for NewClient in a way that requires a code change to preserve the old behaviour. I've updated the PR's title to reflect that.

I agree that it makes sense to have this as a default, since not all changes to the environment document such as editing segments will cause a real-time update. I'll defer to @gagantrivedi for a decision on this.

[gagantrivedi]

since not all changes to the environment document such as editing segments will cause a real-time update

I don't think that's true? ref: https://github.com/Flagsmith/flagsmith/blob/main/api/environments/tasks.py#L26
If we really want to support this, we will have to add another config option, something like WithRealtimeAndSSE.

[rolodato]

I don't think that's true? ref: https://github.com/Flagsmith/flagsmith/blob/main/api/environments/tasks.py#L26

TIL - fixed in Flagsmith/flagsmith#5194