Improve performance of demo workspace - Rename getImageAbsoluteURIOrBase64 function (#6282)

### Description

1. This PR is a continuation of a previous PR:
https://github.com/twentyhq/twenty/pull/6201#pullrequestreview-2175601222

2. One test case was removed here:
`packages/twenty-front/src/utils/image/__tests__/getImageAbsoluteURI.test.ts`
because since we are not handling base64 images anymore, the result is
the same of the last test case. Would you rather we update the test
instead?


### Refs

- #3514
- https://github.com/twentyhq/twenty/pull/6201

### Demo


https://www.loom.com/share/4f32b535c77a4d418e319b095d09452c?sid=df34adf8-b013-44ef-b794-d54846f52d2d

Fixes #3514

---------

Co-authored-by: gitstart-twenty <gitstart-twenty@users.noreply.github.com>

packages/twenty-emails/src/utils/getImageAbsoluteURI.ts

@@ -0,0 +1,16 @@
+export const getImageAbsoluteURI = (
+  imageUrl?: string | null,
+  serverUrl?: string,
+) => {
+  if (!imageUrl) {
+    return null;
+  }
+
+  if (imageUrl?.startsWith('https:')) {
+    return imageUrl;
+  }
+
+  return serverUrl?.endsWith('/')
+    ? `${serverUrl.substring(0, serverUrl.length - 1)}/files/${imageUrl}`
+    : `${serverUrl || ''}/files/${imageUrl}`;
+};