Hi, 

Go to: odoo/addons/web/static/lib/fullcalendar/interaction/main.js

from line 1015, you will see this: 
dragging.emitter.on('pointerdown', this.handlePointerDown);
dragging.emitter.on('dragstart', this.handleDragStart);
dragging.emitter.on('dragmove', this.handleDragMove);
dragging.emitter.on('pointerup', this.handlePointerUp);
dragging.emitter.on('dragend', this.handleDragEnd);

put off instead of on for lines related to dragging, you will have this:

dragging.emitter.on('pointerdown', this.handlePointerDown);
dragging.emitter.on('dragstart', this.handleDragStart);
dragging.emitter.off('dragmove', this.handleDragMove);
dragging.emitter.on('pointerup', this.handlePointerUp);
dragging.emitter.on('dragend', this.handleDragEnd);

You will notice that Drag option isn't possible anymore in calendar view.
If you want to disable spreading out the record in calendar view, you will have to disable dragend too.

Hope this helps.