Generalize IRGen test yet more

Author: DougGregor

test/IRGen/isolated_conformance.swift

@@ -14,7 +14,7 @@ protocol P {
 // CHECK-SAME: ptr @"$s20isolated_conformance1XVMn"
 // CHECK-SAME: ptr @"$s20isolated_conformance1XVyxGAA1PAAWP
 // CHECK-SAME: i32 524288
-// CHECK-SAME: symbolic ScM"
+// CHECK-SAME: ScM
 // CHECK-SAME: $sScMs11GlobalActorsMc"
 @MainActor
 struct X<T>: isolated P {