audit: check for HOMEBREW_PREFIX test path usage.
audit: check for HOMEBREW_PREFIX test path usage.

This is also not allowed.

As seen in https://github.com/Homebrew/homebrew-core/pull/6996.

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