update.sh: don't cleanup on update for developers.
update.sh: don't cleanup on update for developers.

We’re defining developers as people who have run a dev-cmd at least
once.

vitorgalvao/brew,EricFromCanada/brew,jmsundar/brew,palxex/brew,ilovezfs/brew,hanxue/linuxbrew,claui/brew,MikeMcQuaid/brew,muellermartin/dist,mahori/brew,aw1621107/brew,EricFromCanada/brew,reitermarkus/brew,DomT4/brew,reitermarkus/brew,pseudocody/brew,rwhogg/brew,gregory-nisbet/brew,vitorgalvao/brew,jmsundar/brew,EricFromCanada/brew,sjackman/homebrew,maxim-belkin/brew,hanxue/linuxbrew,vitorgalvao/brew,amar-laksh/brew_sudo,Homebrew/brew,tonyg/homebrew,MikeMcQuaid/brew,mahori/brew,DomT4/brew,claui/brew,zmwangx/brew,alyssais/brew,konqui/brew,alyssais/brew,muellermartin/dist,toonetown/homebrew,rwhogg/brew,alyssais/brew,palxex/brew,DomT4/brew,aw1621107/brew,mgrimes/brew,aw1621107/brew,JCount/brew,MikeMcQuaid/brew,rwhogg/brew,maxim-belkin/brew,nandub/brew,Homebrew/brew,ilovezfs/brew,toonetown/homebrew,Linuxbrew/brew,mahori/brew,reitermarkus/brew,reelsense/brew,mgrimes/brew,hanxue/linuxbrew,claui/brew,Linuxbrew/brew,Homebrew/brew,muellermartin/dist,maxim-belkin/brew,Linuxbrew/brew,bfontaine/brew,pseudocody/brew,amar-laksh/brew_sudo,konqui/brew,amar-laksh/brew_sudo,reitermarkus/brew,sjackman/homebrew,reelsense/brew,MikeMcQuaid/brew,Homebrew/brew,ilovezfs/brew,mahori/brew,pseudocody/brew,nandub/brew,vitorgalvao/brew,palxex/brew,toonetown/homebrew,tonyg/homebrew,bfontaine/brew,sjackman/homebrew,EricFromCanada/brew,tonyg/homebrew,konqui/brew,JCount/brew,zmwangx/brew,JCount/brew,gregory-nisbet/brew,nandub/brew,Linuxbrew/brew,konqui/brew,zmwangx/brew,nandub/brew,JCount/brew,claui/brew,gregory-nisbet/brew,mgrimes/brew,sjackman/homebrew,jmsundar/brew,DomT4/brew,bfontaine/brew,reelsense/brew