JIT: Allow cloning addresses even before initobj (#79341)

Roslyn emits ldloca + dup + initobj when initializing structs. Normally
we clone address trees instead of creating a local for them (which will
address expose the local), but we treat this initobj pattern specially.

Remove this special treatment. It means we sometimes end up with
slightly larger code because we no longer have a register with the
address in it (could potentially be fixed by CSE), but avoiding the
address exposure seems like the right trade off to me.

Fix #42354
Fix #57055

Author: jakobbotsch

src/coreclr/jit/importer.cpp

@@ -8387,8 +8387,7 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                     {
                         clone = true;
                     }
-                    else if (op1->TypeIs(TYP_BYREF, TYP_I_IMPL) && impIsAddressInLocal(op1) &&
-                             (OPCODE)impGetNonPrefixOpcode(codeAddr + sz, codeEndp) != CEE_INITOBJ)
+                    else if (op1->TypeIs(TYP_BYREF, TYP_I_IMPL) && impIsAddressInLocal(op1))
                     {
                         // We mark implicit byrefs with GTF_GLOB_REF (see gtNewFieldRef for why).
                         // Avoid cloning for these.