Daemon plot_labels() for faster start (#9057)

* Daemon `plot_labels()` for faster start

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update train.py

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

utils/plots.py

@@ -340,7 +340,6 @@ def plot_val_study(file='', dir='', x=None):  # from utils.plots import *; plot_
 
 
 @try_except  # known issue https://github.com/ultralytics/yolov5/issues/5395
-@Timeout(30)  # known issue https://github.com/ultralytics/yolov5/issues/5611
 def plot_labels(labels, names=(), save_dir=Path('')):
     # plot dataset labels
     LOGGER.info(f"Plotting labels to {save_dir / 'labels.jpg'}... ")