update submodules with --init flag

This updates `pkg/git`'s submodule updating to also `git submodule init` recursively.
Before submodules were not cloned recursively.

Fixes #3320

pkg/git/git.go

@@ -192,10 +192,7 @@ func SubmoduleFetch(logger *zap.SugaredLogger, spec FetchSpec) error {
  return fmt.Errorf("failed to change directory with path %s; err: %w", spec.Path, err)
  }
  }
- if _, err := run(logger, "", "submodule", "init"); err != nil {
- return err
- }
- updateArgs := []string{"submodule", "update", "--recursive"}
+ updateArgs := []string{"submodule", "update", "--recursive", "--init"}
  if spec.Depth > 0 {
  updateArgs = append(updateArgs, fmt.Sprintf("--depth=%d", spec.Depth))
  }