Disable AEGs inside xcode_swift_toolchain

Because of the complexity, I would like to disable AEGs in this rule and proceed with the rest of the migration and flip the flag. I'll come back in the near future to enable them and add `toolchain` param to the affected actions.

PiperOrigin-RevId: 567319616
(cherry picked from commit ee7f493)

swift/toolchains/xcode_swift_toolchain.bzl

@@ -952,6 +952,8 @@ for incremental compilation using a persistent mode.
                     fragment = "apple",
                 ),
             ),
+            # TODO(b/301253335): Enable AEGs later.
+            "_use_auto_exec_groups": attr.bool(default = False),
         },
     ),
     doc = "Represents a Swift compiler toolchain provided by Xcode.",