Fix variable initialization order in snapshot-harness aliasing pointers

[tautschnig]

The root cause was in the topological sort implementation. The dfs() method enforced that seen and inserted sets must be empty on entry (via PRECONDITION) and would clear them on exit. However, topological_sort() calls dfs() multiple times in a loop for each item in the input collection. This meant only the first item was sorted correctly; subsequent items would fail the precondition or produce incorrect results.

The fix moves the set clearing logic to the beginning of topological_sort(), ensuring a fresh DFS traversal for the entire collection while allowing the DFS to maintain state across recursive calls within a single item's dependency graph.

Co-authored-by: Kiro autonomous agent

Fixes: #4978

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[Copilot]

Pull request overview

This PR stabilizes the memory-snapshot harness symbol ordering traversal and re-enables two snapshot-harness regression tests as CORE by making their output matching less brittle.

Changes:

• Reset preordert traversal state once per sort() call (instead of per dfs() invocation) to ensure a fresh, consistent traversal across the full input.
• Promote snapshot-harness regression tests from KNOWNBUG to CORE.
• Relax regression output matching for pointer dereference IDs from a fixed number to \d+, and remove outdated known-bug commentary blocks.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/goto-harness/memory_snapshot_harness_generator.h	Clears seen/inserted at the start of preordert::sort() to ensure traversal state is reset once per sort.
regression/snapshot-harness/dynamic-array-int/test.desc	Marks test as CORE and makes pointer-dereference property ID matching robust to numbering changes.
regression/snapshot-harness/dynamic-array-int-ordering/test.desc	Same as above for the ordering-focused variant.

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