test: Add missing check for empty stderr in util tester #32327

Now that wine support was removed from the CI in 25b56fd9b469f8e5d36f0132c3b79a5214e3372a, it can probably be removed from the util tester as well.

If someone really needs this, they can comment the new check out, or submit a patch to add an option/env var to silence the new check.

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32327.

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tACK fadf12a56c294696052c4cb6ee5284030ada7498

I've reviewed the changes and tested on my system

Code Review ACK fadf12a56c294696052c4cb6ee5284030ada7498

Tested ACK fadf12a56c294696052c4cb6ee5284030ada7498

I verified that with this patch, we now raise an exception whenever a ./bitcoin-util call returns an error message and the corresponding test case does not specify that call have a corresponding error_txt.

For example, by removing the error_txt from the grind util test:

diff --git a/test/util/data/bitcoin-util-test.json b/test/util/data/bitcoin-util-test.json
index 83b3c430d53..d840c8fa1fb 100644
--- a/test/util/data/bitcoin-util-test.json
+++ b/test/util/data/bitcoin-util-test.json
@@ -14,7 +14,6 @@
   { "exec": "./bitcoin-util",
     "args": ["grind"],
     "return_code": 1,
-    "error_txt": "Must specify block header to grind",
     "description": ""
   },
   { "exec": "./bitcoin-util",

On master commit 80e6ad9e3023a57a4ef19b7d0edf9ac5be71a584, the test passes:

abubakarismail@Abubakars-MacBook-Pro bitcoin % build/test/util/test_runner.py  

Whereas on this PR fadf12a56c294696052c4cb6ee5284030ada7498, the test fails:

abubakarismail@Abubakars-MacBook-Pro bitcoin % build/test/util/test_runner.py
2025-04-25 15:54:04,490 - ERROR - Unexpected error received: Must specify block header to grind
res: CompletedProcess(args=['/Users/abubakarismail/Desktop/Work/bitcoin-dev/bitcoin/build/bin/./bitcoin-util', 'grind'], returncode=1, stdout='', stderr='Must specify block header to grind\n')
2025-04-25 15:54:07,683 - ERROR - FAILED_TESTCASES:
['']

ACK fadf12a56c294696052c4cb6ee5284030ada7498