bug-fix: Set correct and unique repo meta data

When using unattended-upgrades at least the origin meta data in the
release file shoulb be unique across all registered package repos in
addition it's also good to set the label to something that clearly
identifies the software source.

With this commit the published Release file will look like this:

Origin: packages.fluentbit.io
Label: fluent-bit
Suite: bookworm
Codename: bookworm

packaging/update-apt-repo.sh

@@ -32,11 +32,16 @@ APTLY_REPO_NAME="debify-$CODENAME"
 APTLY_ROOTDIR=$(mktemp -d)
 APTLY_CONFIG=$(mktemp)
 
-# The origin and label fields seem to cover the base directory for the repo and codename.
-# The docs seems to suggest these fields are optional and free-form: https://wiki.debian.org/DebianRepository/Format#Origin
+# The origin and label fields are free text fields that should indicate the heritage of the package repository.
+# They are used in an unattend-upgrade scenario and therefore they should be unique for each package source.
+# Further information can be found here https://wiki.debian.org/DebianRepository/Format & https://wiki.debian.org/UnattendedUpgrades
+# For fluent-bit a valid apt config entry for unattended upgrades is
+# Unattended-Upgrade::Origins-Pattern {
+#   "origin=packages.fluentbit.io,codename=${distro_codename},label=fluent-bit"
+# }
 # They are security checks to verify if they have changed so we match the legacy server.
-APTLY_ORIGIN=". $CODENAME"
-APTLY_LABEL=". $CODENAME"
+APTLY_ORIGIN="packages.fluentbit.io"
+APTLY_LABEL="fluent-bit"
 if [[ "$DEB_REPO" == "debian/bullseye" ]]; then
     # For Bullseye, the legacy server had a slightly different setup we try to reproduce here
     APTLY_ORIGIN="bullseye bullseye"