repro is staging metric files, dvcfiles, etc

[skshetry]

dvc stage add -n foo "echo foo"
git status
dvc repro
git status

$ dvc stage add -n foo "echo foo"
Added stage 'foo' in 'dvc.yaml'                                       

To track the changes with git, run:

	git add dvc.yaml

To enable auto staging, run:

	dvc config core.autostage true

$ git status
On branch master
Untracked files:
  (use "git add <file>..." to include in what will be committed)
	dvc.yaml

nothing added to commit but untracked files present (use "git add" to track)

$ dvc repro 
Running stage 'foo':                                                  
> echo foo
foo
Generating lock file 'dvc.lock'                                       
Updating lock file 'dvc.lock'

To track the changes with git, run:

	git add dvc.lock dvc.yaml

To enable auto staging, run:

	dvc config core.autostage true
Use `dvc push` to send your updates to remote storage.

$ git status
On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
	new file:   dvc.lock
	new file:   dvc.yaml

Regression from #9271.