Tablist bottom margin fix (#10801)

### Bug
The active tab bottom border appeared slightly above the TabList's light
bottom border.

### Investigation
- Initial fix: Adjusted margin-bottom to -1px in Tab component to align
borders
- This fix caused active bottom borders to disappear in tabs wrapped
with ShowPageSubContainerTabListContainer
- Found that ShowPageSubContainerTabListContainer was adding a redundant
bottom border that overlapped with TabList's border

### Solution
- Removed ShowPageSubContainerTabListContainer to eliminate the
redundant border
- Kept the -1px margin-bottom fix in Tab component
- This ensures consistent border behavior across all TabList
implementations

packages/twenty-front/src/modules/ui/layout/tab/components/Tab.tsx

@@ -41,7 +41,7 @@ const StyledTab = styled('button', {
   display: flex;
   gap: ${({ theme }) => theme.spacing(1)};
   justify-content: center;
-  margin-bottom: 0;
+  margin-bottom: -1px;
   padding: ${({ theme }) => theme.spacing(2) + ' 0'};
   pointer-events: ${({ disabled }) => (disabled ? 'none' : '')};
   text-decoration: none;

packages/twenty-front/src/modules/ui/layout/tab/components/TabList.tsx

@@ -33,7 +33,7 @@ const StyledContainer = styled.div`
   border-bottom: ${({ theme }) => `1px solid ${theme.border.color.light}`};
   box-sizing: border-box;
   display: flex;
-  gap: ${({ theme }) => theme.spacing(2)};
+  gap: ${({ theme }) => theme.spacing(1)};
   height: 40px;
   user-select: none;
 `;