[llvm] [VPlan] Expand sequential/regular UMin SCEVs in VPSCEVExpander. (PR #209786)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `cross-project-tests-sie-ubuntu-dwarf5` running on `doug-worker-1b` while building `llvm` at step 2 "checkout".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/163/builds/44925

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 2 (checkout) failure: update (failure)
git version 2.34.1
fatal: Unable to create '/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/.git/index.lock': File exists.

Another git process seems to be running in this repository, e.g.
an editor opened by 'git commit'. Please make sure all processes
are terminated then try again. If it still fails, a git process
may have crashed in this repository earlier:
remove the file manually to continue.
fatal: Unable to create '/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/.git/index.lock': File exists.

Another git process seems to be running in this repository, e.g.
an editor opened by 'git commit'. Please make sure all processes
are terminated then try again. If it still fails, a git process
may have crashed in this repository earlier:
remove the file manually to continue.

```

</details>

https://github.com/llvm/llvm-project/pull/209786