update-report: further improve analytics messaging
update-report: further improve analytics messaging

- Don't output the analytics message and mark it as read if
`HOMEBREW_NO_ANALYTICS_THIS_RUN` is set. This mostly simplifies the
installer code where we can display the message ourselves there rather
than having `brew update` print it out sometimes and not others (i.e.
when there's no system Git installed).
- Use the shell's audible bell to nudge people to actually read this
message (and give them less excuse to complain when they don't).
- Add an extra newline and bold all the analytics messaging so it's
more visible in the output.

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