Mathlib: Set.mem_diff is deprecated and the new mem_sdiff name is ambiguous

In recent Mathlib (v4.35, late 2026) Set.mem_diff is deprecated in favour of Set.mem_sdiff, and Set.mem_setOf_eq in favour of Set.mem_ofPred_eq. With open Filter Set, a bare mem_sdiff gives 'Ambiguous term' because Filter.mem_sdiff also exists, so write Set.mem_sdiff. In the same cleanup measureReal_diff became measureReal_sdiff (h : s₂ ⊆ s₁) (h₂ : MeasurableSet s₂) (h₁ : μ s₁ ≠ ∞ := by finiteness). When a.e.-rewriting a set before taking its measure, use measureReal_congr on an =ᵐ[volume] set equality obtained by filter_upwards [...] with x hx and simp only [..., eq_iff_iff], then prove the iff.