NO-JIRA: workaround(rstudio/rhel): c9s base does not normally have redhat release key (opendatahub-io#2664)

When we update to latest AIPCC bases that don't remove the ``.repo` files, we will be able to remove the COPYs.

```
Red Hat Universal Base Image 9 (RPMs) - BaseOS  0.0  B/s |   0  B     00:00
  Curl error (37): Couldn't read a file:// file for file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release [Couldn't open file /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release]
```

Author: jiridanek

rstudio/rhel9-python-3.12/Dockerfile.cpu

@@ -22,6 +22,7 @@ USER root
 # The Quay-based AIPCC image is "repo-less" by default (https://gitlab.com/redhat/rhel-ai/core/base-images/app#repositories), so dnf cannot upgrade or install packages.
 # By copying ubi.repo from the public UBI 9 image, we enable package management for upgrades and installations.
 COPY --from=ubi-repos /etc/yum.repos.d/ubi.repo /etc/yum.repos.d/ubi.repo
+COPY --from=ubi-repos /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release
 
 # upgrade first to avoid fixable vulnerabilities begin
 # Problem: The operation would result in removing the following protected packages: systemd

rstudio/rhel9-python-3.12/Dockerfile.cuda

@@ -22,6 +22,7 @@ USER root
 # The Quay-based AIPCC image is "repo-less" by default (https://gitlab.com/redhat/rhel-ai/core/base-images/app#repositories), so dnf cannot upgrade or install packages.
 # By copying ubi.repo from the public UBI 9 image, we enable package management for upgrades and installations.
 COPY --from=ubi-repos /etc/yum.repos.d/ubi.repo /etc/yum.repos.d/ubi.repo
+COPY --from=ubi-repos /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release
 
 # upgrade first to avoid fixable vulnerabilities begin
 # Problem: The operation would result in removing the following protected packages: systemd