Move transient lifetime into OirSDFGBuilder

Transients are added in OirSDFGBuilder, where no array lifetime is
configured. After building that SDFG, the lifetime of all transients is
manually set to `Persistent` (which is an optimization leading to less
frequent memory allocation in case a kernel is called multiple times).
In this commit we directly specify the transient's lifetime when
building the SDFG.

src/gt4py/cartesian/backend/dace_backend.py

@@ -151,10 +151,6 @@ def _pre_expand_transformations(gtir_pipeline: GtirPipeline, sdfg: dace.SDFG, la
         sdfg.add_state(gtir_pipeline.gtir.name)
         return sdfg
 
-    for array in sdfg.arrays.values():
-        if array.transient:
-            array.lifetime = dace.AllocationLifetime.Persistent
-
     sdfg.simplify(validate=False)
 
     _set_expansion_orders(sdfg)

src/gt4py/cartesian/gtc/dace/oir_to_dace.py

@@ -171,6 +171,7 @@ def visit_Stencil(self, node: oir.Stencil):
                 ],
                 dtype=data_type_to_dace_typeclass(decl.dtype),
                 transient=True,
+                lifetime=dace.AllocationLifetime.Persistent,
                 debuginfo=get_dace_debuginfo(decl),
             )
         self.generic_visit(node, ctx=ctx)