Bound ISL operations during DeLICM scalar collapsing (#203073)

The IslMaxOperationsGuard in DeLICM previously covered only the zone
analysis performed in computeZone(). The subsequent greedyCollapse() ->
collapseScalarsToStore() path calls computeScalarReachingOverwrite(),
which performs an unbounded ISL lexmin().
Share a single[already present], dormant IslMaxOperationsGuard across
both regions and arm it narrowly around each operation intensive
computation via IslQuotaScope, so the same operations budget covers both
computeZone() and the scalar collapsing. When the quota is exceeded
during scalar collapsing, bail out cleanly: increment DeLICMOutOfQuota
and emit an "OutOfQuota" analysis remark.

Fixes: https://github.com/llvm/llvm-project/issues/202045
GitOrigin-RevId: 59d7709ee9352df286bfb9b7a3b97c38deae5495