luci-app-radicale2, rpcd-mod-rad2-enc: drop packages

luci-app-radicale2, rpcd-mod-rad2-enc: drop packages

Radicale2 has been dropped from the packages feed as it fails to compile
due to PEP 625 compliance issues.

While the package compiles locally with lowercase filenames, the build
system expects uppercase names. However, PEP 625 enforces lowercase for
distribution filenames (sdists/wheels).

Since radicale3 is available as a replacement, radicale2 is being
removed. LuCI support for radicale3 will be added shortly.

Signed-off-by: Josef Schlehofer <redacted>