Remove dependency on dhcp-client (ISC DHCP) and use dhcpcd instead

Jira: https://issues.redhat.com/browse/RHEL-26304

Cloud-init 24.1 and above versions supports dhcpcd since ISC DHCP is not
maintained any more and has already reached its EOL. Please see upstream
cloud-init commit
21b2b6e4423b ("feat(dhcp): Add support for dhcpcd (#4746)") and PR
https://github.com/canonical/cloud-init/pull/4746

and also https://www.isc.org/blogs/isc-dhcp-eol/ .

Also dhcpcd is the default dhcp client for cloud-init. Please see the commit
6d61b63f34bc83 ("feat(dhcp): Make dhcpcd the default dhcp client (#4912)")

Therefore, change the downstream spec file to remove dependency on dhcp-client
and add a dependency on dhcpcd instead.

X-downstream-only: true

Signed-off-by: Ani Sinha <anisinha@redhat.com>