[BCK-504] Insights: move insert variables selects into the toolbar

Priority: Low Effort: 5 Type: Feature

Move the insert variables select controls from their current location into the toolbar for better accessibility and UI consistency in the insights panel.

Asana Task: https://app.asana.com/1/1206648675960041/project/1208204369345947/task/1210626488464834 BCK ID: BCK-504

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Migrated from Asana