fix: [compose-core] apply bash syntax improvements

bin/compose-core

@@ -1907,7 +1907,7 @@ _run_service_relation () {
 
     base_script_name=$(charm.has_relation_hook "$charm" "$relation_name" relation-joined) || true
     target_script_name=$(charm.has_relation_hook "$target_charm" "$relation_name" relation-joined) || true
-    [ "$base_script_name" -o "$target_script_name" ] || return 0
+    [ -n "$base_script_name" ] || [ -n "$target_script_name" ] || return 0
 
     relation_dir=$(get_relation_data_dir "$service" "$target_service" "$relation_name") || return 1
     RELATION_DATA_FILE=$(get_relation_data_file "$service" "$target_service" "$relation_name" "$relation_config") || return 1
@@ -3218,8 +3218,8 @@ _get_docker_compose_mixin_from_metadata_cached() {
 
     image=$(echo "$metadata" | shyaml get-value "docker-image" 2>/dev/null)
     [ "$image" == "None" ] && image=""
-    if [ "$image" ]; then
-        if [ "$subordinate" ]; then
+    if [ -n "$image" ]; then
+        if [ -n "$subordinate" ]; then
             err "Subordinate charm can not have a ${WHITE}docker-image${NORMAL} value."
             return 1
         fi
@@ -4541,8 +4541,7 @@ if [ "${PIPESTATUS[0]}" != 0 ]; then
     exit 1
 fi
 
-
-if [ "$action" == "run" -a "${#services_args}" != 0 ]; then
+if [ "$action" == "run" ] && [ "${#services_args}" != 0 ]; then
     charm=$(get_service_charm "${services_args[0]}") || exit 1
     metadata=$(charm.metadata "$charm") || exit 1
     SERVICE_TYPE="$(printf "%s" "$metadata" | shyaml get-value type 2>/dev/null)" || true