Move existing tests that may use Enzyme to nopre group

Instead of creating new tests, this moves existing tests that could
potentially use Enzyme through default autodiff settings to the nopre group:

- Basic PolyAlgorithms: Uses RobustMultiNewton() and FastShortcutNonlinearPolyalg()
- PolyAlgorithms Autodiff: Tests autodiff with polyalgorithms
- 23 Test Problems: PolyAlgorithms: Tests with default polyalgorithms
- ForwardDiff.jl Integration: Tests with FastShortcutNonlinearPolyalg() and nothing
- Ensemble Nonlinear Problems: Uses nothing as algorithm
- Out-of-place Matrix Resizing: Uses polyalgorithms without explicit autodiff
- Inplace Matrix Resizing: Uses polyalgorithms without explicit autodiff
- Default Algorithm Singular Handling: Uses default solver

These tests may trigger Enzyme usage through default autodiff backends,
so moving them to nopre group ensures they don't run on Julia prerelease.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ChrisRackauckas

test/23_test_problems_tests.jl

@@ -39,7 +39,7 @@ end
 export test_on_library, problems, dicts
 end
 
-@testitem "23 Test Problems: PolyAlgorithms" setup=[RobustnessTesting] tags=[:core] begin
+@testitem "23 Test Problems: PolyAlgorithms" setup=[RobustnessTesting] tags=[:nopre] begin
     alg_ops=(RobustMultiNewton(), FastShortcutNonlinearPolyalg())
 
     broken_tests=Dict(alg=>Int[] for alg in alg_ops)

test/core_tests.jl

@@ -17,7 +17,7 @@
     @test sol1.u ≈ sol2.u
 end
 
-@testitem "Basic PolyAlgorithms" tags=[:core] begin
+@testitem "Basic PolyAlgorithms" tags=[:nopre] begin
     f(u, p) = u .* u .- 2
     u0 = [1.0, 1.0]
 
@@ -60,7 +60,7 @@ end
     end
 end
 
-@testitem "PolyAlgorithms Autodiff" tags=[:core] begin
+@testitem "PolyAlgorithms Autodiff" tags=[:nopre] begin
     cache = zeros(2)
     function f(du, u, p)
         cache .= u .* u
@@ -126,7 +126,7 @@ end
     @test SciMLBase.successful_retcode(sol.retcode)
 end
 
-@testitem "Ensemble Nonlinear Problems" tags=[:core] begin
+@testitem "Ensemble Nonlinear Problems" tags=[:nopre] begin
     prob_func(prob, i, repeat) = remake(prob; u0 = prob.u0[:, i])
 
     prob_nls_oop = NonlinearProblem((u, p) -> u .* u .- p, rand(4, 128), 2.0)
@@ -350,7 +350,7 @@ end
     end
 end
 
-@testitem "Out-of-place Matrix Resizing" tags=[:core] begin
+@testitem "Out-of-place Matrix Resizing" tags=[:nopre] begin
     using StableRNGs
 
     ff(u, p) = u .* u .- p
@@ -368,7 +368,7 @@ end
     end
 end
 
-@testitem "Inplace Matrix Resizing" tags=[:core] begin
+@testitem "Inplace Matrix Resizing" tags=[:nopre] begin
     using StableRNGs
 
     fiip(du, u, p) = (du .= u .* u .- p)
@@ -437,7 +437,7 @@ end
     @test sol.retcode == ReturnCode.StalledSuccess
 end
 
-@testitem "Default Algorithm Singular Handling" tags=[:core] begin
+@testitem "Default Algorithm Singular Handling" tags=[:nopre] begin
     f(u, p) = [u[1]^2 - 2u[1] + 1, sum(u)]
     prob = NonlinearProblem(f, [1.0, 1.0])
     sol = solve(prob)

test/enzyme_tests.jl

@@ -62,7 +62,7 @@ compatible(::KINSOL, ::Val{:oop_cache}) = false
 export test_f!, test_f, jacobian_f, solve_with, compatible
 end
 
-@testitem "ForwardDiff.jl Integration" setup=[ForwardADTesting] tags=[:core] begin
+@testitem "ForwardDiff.jl Integration" setup=[ForwardADTesting] tags=[:nopre] begin
     @testset for alg in (
         NewtonRaphson(),
         TrustRegion(),