[BUG] The pkg.list_repo_pkgs method ignores repo arguments

Description
On CentOS 7 or 8 machines, we configure 'excludes=kernel*' in /etc/yum.conf or /etc/dnf/dnf.conf to avoid unintentional upgrade of kernel related RPMs.
With such configuration when calling pkg.list_repo_pkgs with disableexcludes=main fails to list kernel RPMs.
E.g.

salt-call pkg.list_repo_pkgs kernel-modules-extra # fails correctly because kernel* is excluded
salt-call pkg.list_repo_pkgs kernel-modules-extra disableexcludes=main # fails incorrectly (due to unused repo_arg)
salt-call pkg.list_repo_pkgs kernel-modules-extra -- --disableexcludes=main # works however 2nd form above is used by pkg.installed and pkg.install state and execution methods, so those fail to install kernel-modules-extra until the bug is fixed.

https://github.com/saltstack/salt/blob/8df03c17e10940c029350d84b216a5ef5fb54351/salt/modules/yumpkg.py#L863

Setup

# Start a CentOS:8.1.1911 container
curl -o bootstrap-salt.sh -L https://bootstrap.saltstack.com
./bootstrap-salt.sh -P -M git v3002.1
echo 'excludes=kernel*' >> /etc/dnf/dnf.conf

Steps to Reproduce the behavior

salt-call pkg.list_repo_pkgs kernel-modules-extra disableexcludes=main

Expected behavior
The command under steps to reproduce should list kernel-modules-extra RPMs, however it returns empty.
Due to this issue, pkg.install and pkg.installed also fail when trying to get this RPM installed with disableexcludes=main option

Versions Report

</details>

Start at salt/modules/yumpkg.py around the linked line and reproduce the behavior with salt-call pkg.list_repo_pkgs on CentOS with excludes=kernel* configured. Verify that passing disableexcludes=main lists kernel-modules-extra RPMs and that the same option no longer prevents pkg.install and pkg.installed from installing it.