Remove remote_development_feature_flag & release feature

What does this MR do and why?

Remove remote_development_feature_flag & release feature

#391543 (closed)

• Already default_enabled: true on all environments
• Rollout issue: [remote_development_feature_flag] - Create remo... (#391543 - closed)
• Removal discussions [remote_development_feature_flag] - Create remo... (#391543 - closed)

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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