Bug 2115976

On the RHEL9 Edge VM with `insights-client-3.1.7-6.el9_0.noarch` installed, the `insights-client.service` is trying to set memory limits in the ExecStartPost of the service using the cgroup-v1 hierarchy.

```
$ sudo systemctl cat insights-client.service 
# /usr/lib/systemd/system/insights-client.service
# This file is part of insights-client.
#
# Any changes made to this file will be overwritten during a software update. To
# override a parameter in this file, create a drop-in file, typically located at
# /etc/systemd/system/insights-client.service.d/override.conf. Put the desired
# overrides in that file and reload systemd. The next time this service is run
# (either manually or via a systemd timer), the overridden values will be in
# effect.
#
# For more information about systemd drop-in files, see systemd.unit(5).

[Unit]
Description=Insights Client
Documentation=man:insights-client(8)
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/insights-client --retry 3
Restart=no
WatchdogSec=900
CPUQuota=30%
MemoryLimit=2G
TasksMax=300
BlockIOWeight=100
ExecStartPost=-/bin/bash -c "echo 2G >/dev/null 2>&1 > /sys/fs/cgroup/memory/system.slice/insights-client.service/memory.memsw.limit_in_bytes"
ExecStartPost=-/bin/bash -c "echo 1G >/dev/null 2>&1 > /sys/fs/cgroup/memory/system.slice/insights-client.service/memory.soft_limit_in_bytes"
```

Since RHEL 9 is mounting the cgroup-v2 hierarchy by default, these commands in the ExecStartPost fields will always fail.

Unfortunately, I am not a cgroup-v2 expert, but I believe that changing the unit file to use the systemd memory options for cgroup-v2 would be the right path forward.

See:  https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_monitoring_and_updating_the_kernel/assembly_configuring-resource-management-using-systemd_managing-monitoring-and-updating-the-kernel#ref_memory-allocation-configuration-options-with-systemd_assembly_configuring-resource-management-using-systemd_managing-monitoring-and-updating-the-kernel


My proposal:

```
$ sudo systemctl cat insights-client.service 
# /usr/lib/systemd/system/insights-client.service
# This file is part of insights-client.
#
# Any changes made to this file will be overwritten during a software update. To
# override a parameter in this file, create a drop-in file, typically located at
# /etc/systemd/system/insights-client.service.d/override.conf. Put the desired
# overrides in that file and reload systemd. The next time this service is run
# (either manually or via a systemd timer), the overridden values will be in
# effect.
#
# For more information about systemd drop-in files, see systemd.unit(5).

[Unit]
Description=Insights Client
Documentation=man:insights-client(8)
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/insights-client --retry 3
Restart=no
WatchdogSec=900
CPUQuota=30%
MemoryLimit=1G
MemorySwapMax=2G
TasksMax=300
BlockIOWeight=100
```

This does the following:

- removes the ExecStartPost entries
- reduces MemoryLimit to 1G to match the value of `memory.soft_limit_in_bytes` from the removed ExecStartPost command
- adds MemorySwapMax=2G to match the value of `memory.memsw.limit_in_bytes` from the removed ExecStartPost command

I'm not certain that MemoryLimit and MemorySwapMax are direct replacements for the cgroup=-v1 options, but it was the best guess that I made after consulting the Memory Resource Controller docs - https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/memory.html#benefits-and-purpose-of-the-memory-controller


NOTE: this change would only be applicable for RHEL9 as RHEL8 still mounts cgroup-v1 by default