✅ use data urls in serializeAttributes image test cases

replace placeholder image/source src and srcset values with data URLs in serializeAttributes.spec.ts to avoid noisy 404 requests during unit test runs.

Author: BenoitZugmeyer

packages/rum/src/domain/record/serialization/serializeAttributes.spec.ts

@@ -116,10 +116,10 @@ describe('serializeDOMAttributes', () => {
       { html: '<div href="value">', expectedBehavior: 'always-unmasked' },
       { html: '<iframe srcdoc="value">', expectedBehavior: 'maskable' },
       { html: '<div srcdoc="value">', expectedBehavior: 'always-unmasked' },
-      { html: '<img src="value">', expectedBehavior: 'maskable-image' },
-      { html: '<img srcset="value">', expectedBehavior: 'maskable-image' },
-      { html: '<source src="value">', expectedBehavior: 'maskable-image' },
-      { html: '<source srcset="value">', expectedBehavior: 'maskable-image' },
+      { html: '<img src="data:image/gif;base64,R0lGODlhAQABAAAAACw=">', expectedBehavior: 'maskable-image' },
+      { html: '<img srcset="data:image/gif;base64,R0lGODlhAQABAAAAACw= 1x">', expectedBehavior: 'maskable-image' },
+      { html: '<source src="data:image/gif;base64,R0lGODlhAQABAAAAACw=">', expectedBehavior: 'maskable-image' },
+      { html: '<source srcset="data:image/gif;base64,R0lGODlhAQABAAAAACw= 1x">', expectedBehavior: 'maskable-image' },
       { html: '<div src="value">', expectedBehavior: 'always-unmasked' },
       { html: '<div srcset="value">', expectedBehavior: 'always-unmasked' },