fix ci: progress bar console clearing for latest Rich release

[deependujha]

What does this PR do?

closes #21009

Recent Rich versions replaced the internal _live attribute with _live_stack (a list) to support nested Live displays.
This change broke our existing call to self._console.clear_live(), which now only pops one Live instance instead of fully clearing.

This PR updates the clearing logic to:

• Detect whether _live_stack exists (new Rich) and clear it directly.
• Fall back to clear_live() for older Rich versions.

Ensures compatibility across both old and new Rich versions, restoring correct progress bar clearing behavior in CI and live runs.

https://github.com/Textualize/rich/pull/3768/files#diff-8f507d88f3d034716fad069c6a73da25e2915a216a2bdda6db2e8d0c13a0020a

Before submitting

• Was this discussed/agreed via a GitHub issue? (not for typos and docs)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes? (if necessary)
• Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• Did you list all the breaking changes introduced by this pull request?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or minor internal changes/refactors)

PR review

Anyone in the community is welcome to review the PR.
Before you start reviewing, make sure you have read the review guidelines. In short, see the following bullet-list:

Reviewer checklist

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
• Make sure the title is self-explanatory and the description concisely explains the PR
• Add labels and milestones (and optionally projects) to the PR so it can be classified

---

📚 Documentation preview 📚: https://pytorch-lightning--21016.org.readthedocs.build/en/21016/

[deependujha]

@Borda Could you please review this PR?
It addresses the main branch CI failures, and merging it should restore CI to green.

[deependujha]

This PR is dependent on Textualize/rich#3811.

• If that PR is merged first, this PR can be closed, as its primary goal is to handle the breaking change.
• If not, the changes introduced here can be removed after Textualize/rich#3811 is merged.

[deependujha]

this is the current code:

if len(getattr(self._console, "_live_stack", [])) > 0:
    self._console.clear_live()
else:
    self._console.clear_live()

so basically calling clear_live irrespective of condition.

---

the logic was:

• if no attribute _live_stack: means, using earlier version, then call clear_live() always as before.
• else, means, latest breaking version, so only call clear_live() if len > 0. Else, pop from empty array will raise error.

cc: @Borda @bhimrazy