cli: fix css + svg import conflict

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/swift-fishes-rush.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fixed an issue where published frontend packages would end up with an invalid import structure if a single module imported both `.css` and `.svg` files.

packages/cli/src/lib/builder/config.ts

@@ -118,6 +118,7 @@ export async function makeRollupConfigs(
       ),
       output,
       onwarn,
+      makeAbsoluteExternalsRelative: false,
       preserveEntrySignatures: 'strict',
       // All module imports are always marked as external
       external: (source, importer, isResolved) =>