🗃️(teams) remove slug field

After some reflexion, the use of a slug field raises to many
problems without being really needed.

One problem is the slug is made from the group name, but we
don't have unicity on this, so a user might be blocked without
any clue.

We also want to allow group names to be reused (which is already
allowed except for the automatic slug).

The unique ID that will be shared with Service Providers will be
the PK/UUID.

src/frontend/apps/e2e/__tests__/app-desk/teams-create.spec.ts

@@ -93,27 +93,6 @@ test.describe('Teams Create', () => {
     await expect(page).toHaveURL(/\/teams\//);
   });
 
-  test('checks error when duplicate team', async ({ page, browserName }) => {
-    const panel = page.getByLabel('Teams panel').first();
-
-    await panel.getByRole('link', { name: 'Add a team' }).click();
-
-    const teamName = `My duplicate team ${browserName}-${Math.floor(Math.random() * 1000)}`;
-    await page.getByText('Team name').fill(teamName);
-    await page.getByRole('button', { name: 'Create the team' }).click();
-
-    await panel.getByRole('link', { name: 'Add a team' }).click();
-
-    await page.getByText('Team name').fill(teamName);
-    await page.getByRole('button', { name: 'Create the team' }).click();
-
-    await expect(
-      page.getByText(
-        'This name is already used for another group. Please enter another one.',
-      ),
-    ).toBeVisible();
-  });
-
   test('checks 404 on teams/[id] page', async ({ page }) => {
     await page.goto('/teams/some-unknown-team');
     await expect(