Revert "[AssumptionCache] Avoid dangling llvm.assume calls in the cache"

This reverts commit b7d870eae7fdadcf10d0f177faa7409c2e37d776 and the
subsequent fix "[Polly] Fix build after AssumptionCache change (D96168)"
(commit e6810cab09fcbc87b6e5e4d226de0810e2f2ea38).

It caused indeterminism in the output, such that e.g. the
polly-x86_64-linux buildbot failed accasionally.

GitOrigin-RevId: 606aa622b23855784c5db5b48b1c4800467fd851
diff --git a/lib/Analysis/ScopBuilder.cpp b/lib/Analysis/ScopBuilder.cpp
index af81862..96557db 100644
--- a/lib/Analysis/ScopBuilder.cpp
+++ b/lib/Analysis/ScopBuilder.cpp
@@ -1527,7 +1527,7 @@
 void ScopBuilder::addUserAssumptions(
     AssumptionCache &AC, DenseMap<BasicBlock *, isl::set> &InvalidDomainMap) {
   for (auto &Assumption : AC.assumptions()) {
-    auto *CI = dyn_cast_or_null<CallInst>(Assumption.getAssumeCI());
+    auto *CI = dyn_cast_or_null<CallInst>(Assumption);
     if (!CI || CI->getNumArgOperands() != 1)
       continue;