[llvm] [ValueTracking] Refine known bits for linear interpolation patterns (PR #166378)

[Valeriy Savchenko via llvm-commits]

SavchenkoValeriy wrote:

☝️ this test seems to be flaky. We had exactly the same failure earlier: https://lab.llvm.org/buildbot/#/builders/88/builds/17887 and the next build after mine is successful.

https://github.com/llvm/llvm-project/pull/166378