Add yum check for rclone installation

[EricBryann]

PR to fix #6567

When dpkg runs into an error, the code defaults to yum, and some don't have yum installed, resulting in
sudo: yum: command not found

This PR checks for existence of yum before rclone install

Tested (run the relevant ones):

• Code formatting: install pre-commit (auto-check on commit) or bash format.sh
• Any manual or new tests for this PR (please specify below)
• All smoke tests: /smoke-test (CI) or pytest tests/test_smoke.py (local)
• Relevant individual tests: /smoke-test -k test_name (CI) or pytest tests/test_smoke.py::test_name (local)
• Backward compatibility: /quicktest-core (CI) or pytest tests/smoke_tests/test_backward_compat.py (local)

[kevinmingtarja]

Thanks for the contribution @EricBryann!

Let's add a smoke test on AWS for this :)

Some pointers:

• rclone is needed only with MOUNT_CACHED mode (or on arm64 arch),
• So you can copy test_kubernetes_storage_mounts_cached as a starting point
• Let's test with two different AMIs that are different linux distros, one with dpkg, the other with yum. We can take ubuntu and amazon linux 2023 for example

[kevinmingtarja]

/smoke-test -k storage_mounts_cached --aws

[kevinmingtarja]

To reduce duplication, could we use @pytest.mark.parametrize to parametrize just the image id (and the comment too), because everything else is the same.

[kevinmingtarja]

Thanks for the smoke test! This actually catches a minor issue in our code. Turns out, Amazon Linux 2023 does not have fusermount3 installed by default (while ubuntu does) so this test actually errors, so let's add a step to do that before doing rclone mount.

Minimal repro with the same image id:

% sky launch --infra aws/us-east-2 --image-id ami-0a5a5b7e2278263e5 which fusermount3
Command to run: which fusermount3
Considered resources (1 node):
------------------------------------------------------------------------------
 INFRA             INSTANCE      vCPUs   Mem(GB)   GPUS   COST ($)   CHOSEN
------------------------------------------------------------------------------
 AWS (us-east-2)   m6i.2xlarge   8       32        -      0.38          ✔
------------------------------------------------------------------------------
Launching a new cluster 'sky-7f54-kevin'. Proceed? [Y/n]:
⚙︎ Launching on AWS us-east-2 (us-east-2a,us-east-2b,us-east-2c).
└── Instance is up.
✓ Cluster launched: sky-7f54-kevin.  View logs: sky logs --provision sky-7f54-kevin
⚙︎ Syncing files.
⚙︎ Job submitted, ID: 1
├── Waiting for task resources on 1 node.
└── Job started. Streaming logs... (Ctrl-C to exit log streaming; job will not be killed)
(sky-cmd, pid=27528) /usr/bin/which: no fusermount3 in (/home/ubuntu/miniconda3/bin:/home/ubuntu/miniconda3/condabin:/home/ubuntu/.local/bin:/home/ubuntu/bin:/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin)
✓ Job finished (status: SUCCEEDED).