Merge bitcoin/bitcoin#34492: ci: Drop valgrind fuzz from GHA matrix

faa4ab113c ci: Drop valgrind fuzz from GHA matrix (MarcoFalke)

Pull request description:

  The valgrind fuzz task is problematic, because:

  * It is redundant with the msan fuzz task, which has std lib hardening enabled, so often UB is diagnosed before it even happens in the valgrind task.
  * All issues so far found by the valgrind fuzz task were also found by the hardened msan fuzz task.
  * All other issues were false-positives, which are hard to debug, and confusing and tedious to work around.

  I don't think there is any value in asking pull request authors to debug valgrind false-positives that they triggered by accident. So remove the task for now.

  I know that there are some devs, who like to keep the task, but if the task is kept, it should come with clear instructions on how to deal with false-postives in pull requests.

  I am not proposing to remove the config itself, and I am happy to continue maintaining it, like it was done before. However, as of now, running it in the GHA matrix is of negative or questionable benefit.

ACKs for top commit:
  l0rinc:
    ACK faa4ab113c
  fanquake:
    ACK faa4ab113c - hopefully we can revisit re-adding soon. To be clear, I don't agree with the rationale from #34304, or the initial changes there. The case here, and the fact that it is causing disruption in this repo, is more pressing.

Tree-SHA512: 59272f4b5b01c3b8ee6078ea635441f17776d4d8923f1adacdabdbb00bd2eb0234b30dc5b27938e29f8e79b3c3bebed5f339ae36c2c8fb17ea9d3a2884bee986

.github/workflows/ci.yml

@@ -578,12 +578,6 @@ jobs:
             timeout-minutes: 240
             file-env: './ci/test/00_setup_env_native_fuzz.sh'
 
-          - name: 'Valgrind, fuzz'
-            cirrus-runner: 'ghcr.io/cirruslabs/ubuntu-runner-amd64:24.04-md'
-            fallback-runner: 'ubuntu-24.04'
-            timeout-minutes: 240
-            file-env: './ci/test/00_setup_env_native_fuzz_with_valgrind.sh'
-
           - name: 'previous releases'
             cirrus-runner: 'ghcr.io/cirruslabs/ubuntu-runner-amd64:24.04-md'
             fallback-runner: 'ubuntu-24.04'