exp: speed up repro execution with untracked directories in workspace

When large untracked directories are present in the workspace, a lot of
time is spent collecting untracked files in `scm.status` and `scm.is_dirty`.

dvc/repo/experiments/__init__.py

@@ -196,7 +196,7 @@ class Experiments:
                             branch_name = ExpRefInfo.from_ref(branch).name
                         else:
                             branch_name = f"{resume_rev[:7]}"
-                        if self.scm.is_dirty():
+                        if self.scm.is_dirty(untracked_files=False):
                             logger.info(
                                 "Modified checkpoint experiment based on "
                                 "'%s' will be created",
@@ -398,7 +398,7 @@ class Experiments:
             self.reset_checkpoints()
 
         if not (queue or tmp_dir or machine):
-            staged, _, _ = self.scm.status()
+            staged, _, _ = self.scm.status(untracked_files="no")
             if staged:
                 logger.warning(
                     "Your workspace contains staged Git changes which will be "

dvc/repo/experiments/executor/base.py

@@ -640,7 +640,7 @@ class BaseExecutor(ABC):
     ):
         """Commit stages as an experiment and return the commit SHA."""
         rev = scm.get_rev()
-        if not scm.is_dirty():
+        if not scm.is_dirty(untracked_files=False):
             logger.debug("No changes to commit")
             raise UnchangedExperimentError(rev)
 

dvc/repo/plots/diff.py

@@ -5,7 +5,7 @@ def _revisions(repo, revs, experiment):
         if baseline:
             revisions.append(baseline[:7])
     if len(revisions) <= 1:
-        if len(revisions) == 0 and repo.scm.is_dirty():
+        if len(revisions) == 0 and repo.scm.is_dirty(untracked_files=False):
             revisions.append("HEAD")
         revisions.append("workspace")
     return revisions