Qualify issuccess as LinearAlgebra.issuccess to fix QA ExplicitImports failure

[ChrisRackauckas-Claude]

Note: This PR should be ignored until reviewed by @ChrisRackauckas.

Problem

The QA test group (GROUP=QA) fails on main in ExplicitImports' no_implicit_imports check:

no_implicit_imports: Error During Test at .../SciMLTesting/y2DHi/src/SciMLTesting.jl:816
  Test threw exception
  Expression: check(pkg; get(ei_kwargs, name, (;))...) === nothing
  ImplicitImportsException
  Module `LinearSolve` is relying on the following implicit imports:
  * `issuccess` which is exported by `LinearAlgebra`

Test Summary:                                  | Pass  Error  Broken  Total   Time
Quality Assurance                              |   14      1       2     17  45.4s
...
    ExplicitImports                            |    4      1       1      6  18.2s
      no_implicit_imports                      |           1              1   4.5s
ERROR: Package LinearSolve errored during testing

Cause

Commit c75997b (#1078, GESVFactorization + dense LU pivot-buffer reuse) added an unqualified if !issuccess(luf) in SciMLBase.solve!(cache::LinearCache, alg::GESVFactorization) in src/factorization.jl. issuccess is not explicitly imported, so ExplicitImports flags it as an implicit import from LinearAlgebra.

Fix

One-line change: qualify the call as LinearAlgebra.issuccess(luf), matching the existing qualified use earlier in the same file.

Verification

GROUP=QA run with this fix, Julia 1.12 (the 2 broken entries are pre-existing):

Test Summary:     | Pass  Broken  Total   Time
Quality Assurance |   15       2     17  41.1s
Test Summary: | Pass  Broken  Total   Time
JET Tests     |   27       8     35  45.4s
     Testing LinearSolve tests passed

🤖 Generated with Claude Code