fix(flowchart-v2): fix arrowMarkerAbsolute=true

The if-check for arrowMarkerAbsolute in the flowchart-v2 code is in
dagre-wrapper. Unfortunately, I can't seem to find a way to find the
local conf (e.g. the one set via `flowRenderer.setConf()`, so instead
I'm using global mermaid config from `src/config`.

Flowchart v1 arrowMarkerAbsolute=true is still broken, but I'm not
really sure how to fix that.

cypress/integration/other/configuration.spec.js

@@ -95,7 +95,7 @@ describe('Configuration', () => {
     });
     it('should handle arrowMarkerAbsolute set to true', () => {
       renderGraph(
-        `graph TD
+        `flowchart TD
         A[Christmas] -->|Get money| B(Go shopping)
         B --> C{Let me think}
         C -->|One| D[Laptop]