Assuming all our devs are already at least on F40 on their workstations,
just finally drop the gdb-headless workaround.  The original bug
(#2310156) was fixed in both F40 and 41.

This also simplifies the special-casing for "rpm -e" a bit.

This plugin of ours, when installed in a container, currently causes
transaction errors (simply because IMA isn't supported in containers
currently).

This isn't immediately visible unless another dnf transaction would be
run, either in the Dockerfile itself, or in a custom podman container
made from the resulting "rpm" image tag.  Note that the tests themselves
aren't affected by this since they currently don't install any
IMA-signed packages.

In any case, the plugin is unnecessary in the test image, make sure to
remove it.

The reason it's installed is through the ima-evm-utils-devel package
(which pulls in ima-evm-utils-libs which pulls in the plugin).  This is
a new thing on F41 so only handle it there.