MINOR: [C++][CI] Work around bug in conda-forge benchmark package (#41987)

### Rationale for this change

Work around bug in version 1.8.4 of the benchmark package: conda-forge/benchmark-feedstock#36

### Are these changes tested?

By regular CI jobs.

### Are there any user-facing changes?

No.

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Jacob Wujciak-Jens <jacob@wujciak.de>

Author: pitrou

.github/workflows/cpp.yml

@@ -21,6 +21,7 @@ on:
   push:
     paths:
       - '.github/workflows/cpp.yml'
+      - 'ci/conda_env_*'
       - 'ci/docker/**'
       - 'ci/scripts/cpp_*'
       - 'ci/scripts/install_azurite.sh'
@@ -35,6 +36,7 @@ on:
   pull_request:
     paths:
       - '.github/workflows/cpp.yml'
+      - 'ci/conda_env_*'
       - 'ci/docker/**'
       - 'ci/scripts/cpp_*'
       - 'ci/scripts/install_azurite.sh'

ci/conda_env_cpp.txt

@@ -21,7 +21,7 @@ azure-identity-cpp>=1.6.0
 azure-storage-blobs-cpp>=12.10.0
 azure-storage-common-cpp>=12.5.0
 azure-storage-files-datalake-cpp>=12.9.0
-benchmark>=1.6.0
+benchmark>=1.6.0,!=1.8.4
 boost-cpp>=1.68.0
 brotli
 bzip2