Add package logic for Amazon Linux 2

This commit adds logic for Amazon Linux 2 to Beaker's install_ and
uninstall_package methods. (Note: AL2 is referred to in Vanagon and ABS
as Amazon Linux 7, in reference to the assumed compatibility with Red
Hat Enterprise Linux 7.)

lib/beaker/host/unix/pkg.rb

@@ -85,7 +85,7 @@ def install_package(name, cmdline_args = '', version = nil, opts = {})
     when /amazon-2023|el-(8|9|1[0-9])|fedora/
       name = "#{name}-#{version}" if version
       execute("dnf -y #{cmdline_args} install #{name}", opts)
-    when /centos|redhat|el-[1-7]-/
+    when /amazon-7|centos|redhat|el-[1-7]-/
       name = "#{name}-#{version}" if version
       execute("yum -y #{cmdline_args} install #{name}", opts)
     when /ubuntu|debian/
@@ -167,7 +167,7 @@ def uninstall_package(name, cmdline_args = '', opts = {})
       execute("zypper --non-interactive rm #{name}", opts)
     when /amazon-2023|el-(8|9|1[0-9])|fedora/
       execute("dnf -y #{cmdline_args} remove #{name}", opts)
-    when /centos|redhat|el-[1-7]-/
+    when /amazon-7|centos|redhat|el-[1-7]-/
       execute("yum -y #{cmdline_args} remove #{name}", opts)
     when /ubuntu|debian/
       execute("apt-get purge #{cmdline_args} -y #{name}", opts)