Merge bitcoin/bitcoin#35014: test: remove macOS REDUCE_EXPORTS exception workaround

b555a0b789 test: remove macOS REDUCE_EXPORTS exception workaround (Alfonso Roman Zubeldia)

Pull request description:

  Fixes #34723.

    The underlying fix was merged in #34977 (subtree update from bitcoin-core/libmultiprocess#268). This PR
    removes the test workaround that accepted the degraded unknown non-KJ exception of type: `kj::Exception`
    error message on Darwin.

    Tested: `interface_ipc_mining.py` passes on macOS (arm64) with REDUCE_EXPORTS=ON.

ACKs for top commit:
  achow101:
    ACK b555a0b789
  ryanofsky:
    Code review ACK b555a0b789. Thanks for the fixes!
  w0xlt:
    ACK b555a0b789

Tree-SHA512: fa5a316db2ed9ce67dabbd7c529818664dfca01faeb7aff9c5cbb9a1b876de3f498f675eae4bdb74de71e73b7b8cf8cc85c44f520e59f9e3e7a6d6c442ea8273

test/functional/test_framework/ipc_util.py

@@ -10,7 +10,6 @@ from dataclasses import dataclass
 from io import BytesIO
 from pathlib import Path
 import shutil
-import platform
 from typing import Optional
 
 from test_framework.messages import CBlock
@@ -161,12 +160,5 @@ async def make_mining_ctx(self):
     return ctx, mining
 
 def assert_capnp_failed(e, description_prefix):
-    if e.description == "remote exception: unknown non-KJ exception of type: kj::Exception":
-        # macOS + REDUCE_EXPORTS bug: Cap'n Proto fails to recognize
-        # its own exception type and returns a generic error instead.
-        # https://github.com/bitcoin/bitcoin/pull/34422#discussion_r2863852691
-        # Assert this only occurs on Darwin until fixed.
-        assert_equal(platform.system(), "Darwin")
-    else:
-        assert e.description.startswith(description_prefix), f"Expected description starting with '{description_prefix}', got '{e.description}'"
+    assert e.description.startswith(description_prefix), f"Expected description starting with '{description_prefix}', got '{e.description}'"
     assert_equal(e.type, "FAILED")