Predeploy hooks not run when deploying individual functions

[sam-throne]

[REQUIRED] Environment info

firebase-tools: From HEAD

Platform: macOS

[REQUIRED] Test case

"functions": [
  {
    "predeploy": "echo PREDEPLOY",
    "source": "build",
  },
]

[REQUIRED] Steps to reproduce

firebase deploy --only functions:myFunction

[REQUIRED] Expected behavior

It should print PREDEPLOY

[REQUIRED] Actual behavior

Nothing is printed

This is a regression introduced by #6011

[blidd-google]

Thanks for bringing this to our attention, follow-up PR here should resolve the issue: #6023.