[AiAssistance] Update FRE disclaimer dialog's sizing behavior

This CL:
* Updates the content itself to have a width.
* Removes setting width / height in the dialog itself and
continuing with MEASURE_CONTENT.

This would allow the content to have a fixed width and
an adjustable height based on its contents.

Fixed: 404234931
Change-Id: I1116689699978efb3e9d37911b74d0e1b2da8147
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6368841
Commit-Queue: Ergün Erdoğmuş <[email protected]>
Auto-Submit: Ergün Erdoğmuş <[email protected]>
Commit-Queue: Wolfgang Beyer <[email protected]>
Reviewed-by: Wolfgang Beyer <[email protected]>

Author: ergunsh

front_end/panels/common/common.css

@@ -6,6 +6,7 @@
 
 
 .fre-disclaimer {
+  width: var(--sys-size-33);
   padding: var(--sys-size-9);
 
   header {

front_end/panels/common/common.ts

@@ -117,7 +117,6 @@ export class FreDialog {
       result.resolve(false);
     });
     dialog.setSizeBehavior(UI.GlassPane.SizeBehavior.MEASURE_CONTENT);
-    dialog.setMaxContentSize(new UI.Geometry.Size(448, 600));
     dialog.setDimmed(true);
     dialog.show();