It seems like you have a two pronged issue. First, you've been tasked with changing a culture. Second, the structures in place support the current "hero" or "cowboy" mentality.
The first task is for you to influence your boss and key people that report to you the value of having a culture that plans, prepares or works towards a future vs. fire fighting. There are hundreds of great business reasons to do this: lower rework; increased innovation; etc. Your job is to present a business case for why moving towards a new way of operating is going to benefit people.
The second task, that can be done in parallel to the the first, is to redesign the structure of culture - performance management, hiring, leadership development, on boarding, etc. - to reflect the focus on thoughtful planning. Instead of rewarding someone for fixing a problem in production, reward people that test before production or that have no issues in production. Praise the behaviors and actions that promote the culture you aspire to. The other side of that coin is to not stand for the "ready, fire, aim" mentality. When I joined Discover, it was an cowboy/crisis culture. People were rewarded for fixing issues that would have been avoided with better planning. It was a culture of late nights and burnout. We worked hard with leaders to alter the rewards, formal and informal, to focus on planning, thoughtfulness, smooth launches, etc. At the same time, we worked hard to promote planning. If there was a crisis in production or once something was launched we ruthlessly sought out the root cause. Not to point fingers, but to continuously uncover the power of planning and mindfulness.
All of this takes time and thoughtful action. It is about ensuring people know the new normal and then creating structures to support it.