CI: Select all packages in sharded tests (#105725)

scripts/ci/backend-tests/pkgs-with-tests-named.sh

@@ -44,7 +44,7 @@ done
 shift $((OPTIND - 1))
 
 if [[ ${#dirs[@]} -eq 0 ]]; then
-    dirs+=("./...")
+    readarray -t dirs <<< "$(find . -type f -name 'go.mod' -exec dirname '{}' ';' | awk '{ print $1 "/..."; }')"
 fi
 if [ -z "$beginningWith" ]; then
     for pkg in "${dirs[@]}"; do

scripts/ci/backend-tests/shard.sh

@@ -100,7 +100,7 @@ if [[ $n -gt $m ]]; then
     exit 1
 fi
 if [[ ${#dirs[@]} -eq 0 ]]; then
-    dirs+=("./...")
+    readarray -t dirs <<< "$(find . -type f -name 'go.mod' -exec dirname '{}' ';' | awk '{ print $1 "/..."; }')"
 fi
 # If dirs is just ("-"), read from stdin instead.
 if [[ ${#dirs[@]} -eq 1 && "${dirs[0]}" == "-" ]]; then