polkit: keep the agent helper units in the main package

Commit 3e423e21e5 ("polkit: enable the agent helper socket") enables
polkit-agent-helper.socket from polkit, but since 03420389ca ("polkit:
Add a separate package for polkit systemd service/dbus config")
polkit-service comes first in PACKAGES and takes the whole systemd unit
directory, so the socket is packaged there. Images that install polkit
without polkit-service then fail in do_rootfs:

  Failed to enable unit: Unit polkit-agent-helper.socket does not exist

Installing polkit-service as well does not help with rpm, as it depends
on polkit, whose postinst then runs before the socket unit is installed.

Only package polkit.service in polkit-service, so the agent helper units
stay in polkit with polkit-agent-helper-1, as FILES:${PN} already
intends.

AI-Generated: Uses Claude Code
Signed-off-by: Ricardo Salveti <ricardo.salveti@oss.qualcomm.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

meta-oe/recipes-extended/polkit/polkit_127.bb

@@ -48,7 +48,7 @@ SYSTEMD_SERVICE:${PN}-service = "${BPN}.service"
 PACKAGES =+ "${PN}-service"
 RDEPENDS:${PN}-service += "polkit"
 FILES:${PN}-service += " \
-    ${systemd_system_unitdir} \
+    ${systemd_system_unitdir}/polkit.service \
     ${sysconfdir}/systemd/system/polkit-virtual-provider.service \
 "