I am trying to facilitate upstream quay.io/ceph/daemon-base and quay.io/ceph/ceph container builds that have regular ARM updates.

This PR (https://github.com/ceph/ceph-container/pull/2102) will do so, but requires some modifications to Shaman to reliably retrieve the latest ARM-compatible repo. To the best of my knowledge, we don't require bleeding edge ARM builds. From what I have seen looking into Shaman, the ARM builds happen with some regularity, and that should be sufficient for development of [Rook](rook.io) on ARM systems (and I think cephadm as well).

Generally, I think `curl -L https://shaman.ceph.com/api/repos/nfs-ganesha/next/latest/centos/8/flavors/ceph_main/repo` should return the bleeding edge. However, if I specify `?arch=aarch64`, I explicitly want the latest ARM build, and I should get a result. For ceph-container it should be okay if the result isn't the same as what would be returned for the equivalent x86 build.

As an example, this is what I saw on March 6, 2023:
```
[
{
"status": "ready",
"sha1": "91dd6865b71bbe99ad828c9c8bae1827922cd2a6",
"extra": {
"build_url": "https://jenkins.ceph.com/job/nfs-ganesha/ARCH=x86_64,AVAILABLE_ARCH=x86_64,AVAILABLE_DIST=centos8,DIST=centos8,MACHINE_SIZE=huge/3427/",
"root_build_cause": "TIMERTRIGGER",
"version": "5-dev.3",
"node_name": "172.21.2.6+braggi06",
"job_name": "nfs-ganesha/ARCH=x86_64,AVAILABLE_ARCH=x86_64,AVAILABLE_DIST=centos8,DIST=centos8,MACHINE_SIZE=huge",
"package_manager_version": "54.34.3-"
},
"url": "https://2.chacra.ceph.com/r/nfs-ganesha/next/91dd6865b71bbe99ad828c9c8bae1827922cd2a6/centos/8/flavors/ceph_main/",
"distro_codename": null,
"modified": "2023-03-04 01:05:01.711522",
"distro_version": "8",
"project": "nfs-ganesha",
"flavor": "ceph_main",
"ref": "next",
"chacra_url": "https://2.chacra.ceph.com/repos/nfs-ganesha/next/91dd6865b71bbe99ad828c9c8bae1827922cd2a6/centos/8/flavors/ceph_main/",
"archs": [
"source",
"x86_64"
],
"distro": "centos"
},
{
"status": "ready",
"sha1": "91dd6865b71bbe99ad828c9c8bae1827922cd2a6",
"extra": {
"build_url": "https://jenkins.ceph.com/job/nfs-ganesha/ARCH=x86_64,AVAILABLE_ARCH=x86_64,AVAILABLE_DIST=centos8,DIST=centos8,MACHINE_SIZE=huge/3425/",
"root_build_cause": "SCMTRIGGER",
"version": "5-dev.3",
"node_name": "172.21.2.6+braggi06",
"job_name": "nfs-ganesha/ARCH=x86_64,AVAILABLE_ARCH=x86_64,AVAILABLE_DIST=centos8,DIST=centos8,MACHINE_SIZE=huge",
"package_manager_version": "54.34.3-"
},
"url": "https://3.chacra.ceph.com/r/nfs-ganesha/next/91dd6865b71bbe99ad828c9c8bae1827922cd2a6/centos/8/flavors/ceph_main/",
"distro_codename": null,
"modified": "2023-03-03 23:21:03.852603",
"distro_version": "8",
"project": "nfs-ganesha",
"flavor": "ceph_main",
"ref": "next",
"chacra_url": "https://3.chacra.ceph.com/repos/nfs-ganesha/next/91dd6865b71bbe99ad828c9c8bae1827922cd2a6/centos/8/flavors/ceph_main/",
"archs": [
"x86_64",
"source"
],
"distro": "centos"
}
]
```

Searching for arm returns no result
```
$ curl -s -L "https://shaman.ceph.com/api/repos/nfs-ganesha/next/latest/centos/8/flavors/ceph_main/repo?arch=aarch64"

504 Gateway Timeout

504 Gateway Timeout

The gateway has timed out.


no repository is ready for: nfs-ganesha/next

```

Whereas searching for x86_64 does return a result:
```
curl -s -L "https://shaman.ceph.com/api/repos/nfs-ganesha/next/latest/centos/8/flavors/ceph_main/repo?arch=x86_64"
[nfs-ganesha]
name=nfs-ganesha packages for $basearch
baseurl=https://2.chacra.ceph.com/r/nfs-ganesha/next/91dd6865b71bbe99ad828c9c8bae1827922cd2a6/centos/8/flavors/ceph_main/$basearch
enabled=1
gpgcheck=0
type=rpm-md

[nfs-ganesha-noarch]
name=nfs-ganesha noarch packages
baseurl=https://2.chacra.ceph.com/r/nfs-ganesha/next/91dd6865b71bbe99ad828c9c8bae1827922cd2a6/centos/8/flavors/ceph_main/noarch
enabled=1
gpgcheck=0
type=rpm-md

[nfs-ganesha-source]
name=nfs-ganesha source packages
baseurl=https://2.chacra.ceph.com/r/nfs-ganesha/next/91dd6865b71bbe99ad828c9c8bae1827922cd2a6/centos/8/flavors/ceph_main/SRPMS
enabled=1
gpgcheck=0
type=rpm-md
```