GH-50189: [C++][CI] Remove Ceph install step (#50190)

### Rationale for this change

Ceph was only used for testing the Skyhook component, which has been removed.

### Are these changes tested?

By existing CI builds.

### Are there any user-facing changes?

No.

* GitHub Issue: #50189

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Raúl Cumplido <raulcumplido@gmail.com>

Author: pitrou

.pre-commit-config.yaml

@@ -299,7 +299,6 @@ repos:
           ?^ci/scripts/download_tz_database\.sh$|
           ?^ci/scripts/install_azurite\.sh$|
           ?^ci/scripts/install_ccache\.sh$|
-          ?^ci/scripts/install_ceph\.sh$|
           ?^ci/scripts/install_chromedriver\.sh$|
           ?^ci/scripts/install_cmake\.sh$|
           ?^ci/scripts/install_conda\.sh$|

ci/docker/ubuntu-22.04-cpp.dockerfile

@@ -176,9 +176,6 @@ RUN /arrow/ci/scripts/install_minio.sh latest /usr/local
 COPY ci/scripts/install_gcs_testbench.sh /arrow/ci/scripts/
 RUN /arrow/ci/scripts/install_gcs_testbench.sh default
 
-COPY ci/scripts/install_ceph.sh /arrow/ci/scripts/
-RUN /arrow/ci/scripts/install_ceph.sh
-
 COPY ci/scripts/install_sccache.sh /arrow/ci/scripts/
 RUN /arrow/ci/scripts/install_sccache.sh unknown-linux-musl /usr/local/bin
 

ci/docker/ubuntu-24.04-cpp.dockerfile

@@ -165,9 +165,6 @@ RUN /arrow/ci/scripts/install_gcs_testbench.sh default
 COPY ci/scripts/install_azurite.sh /arrow/ci/scripts/
 RUN /arrow/ci/scripts/install_azurite.sh
 
-COPY ci/scripts/install_ceph.sh /arrow/ci/scripts/
-RUN /arrow/ci/scripts/install_ceph.sh
-
 COPY ci/scripts/install_sccache.sh /arrow/ci/scripts/
 RUN /arrow/ci/scripts/install_sccache.sh unknown-linux-musl /usr/local/bin