gh-143613: Added highlight (in gray color)to visualization graph of executors.

[priyanshu2282-cyber]

This change adds a gray visual highlight to distinguish cold executors in the Graphviz output produced by sys._dump_tracelets().

• Issue: Add highlighting and colour to the visualisation graph of executors. #143613

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[Fidget-Spinner]

Sorry but this doesn't look right. I don't think cold executors are supposed to be printed in the first place.

Also in the future, could you please ask on the issue if you can take/open a PR for it? I don't know whether Mark is intending to do this issue himself.

[priyanshu2282-cyber]

Thanks for the clarification. I’ll be sure to ask on the issue before opening a PR in the future.