fix: isOss check + minor UI things (#8828)

This PR fixes the isOss check for the licensed users component. It also
addresses two things in the UI:

1. It right-aligns the text on the button so that when we get narrower,
the text doesn't slide to the center. There's a few more things that we
can fix later, though. When you press it, it'll still show the entire
button layout:

![image](https://github.com/user-attachments/assets/ea4606be-614a-455e-921f-45ed8d40df23)
And when you focus it with a keyboard it still looks like a button. 

We can get around that by using a regular button and just styling it a
bit, but making the text align will take some extra jimmying around (not
done in this pr, but got stashed changes for it)

![image](https://github.com/user-attachments/assets/33b2f32b-0027-45bf-84f2-4a5e99ef38b2)

But this is what it'd look like now with centered text: 

![image](https://github.com/user-attachments/assets/fe4c6b28-ede1-4418-a471-c2b6b959aacf)



2. It wraps the entire left column in a `p` tag, because they belong
together. They're not two logical paragraphs. So instead, we wrap them
in spans and surround them in a
p. `Display: contents` makes the p "invisible", so its children act as
if
they're children of the container above it instead.

frontend/src/component/admin/users/UsersHeader/LicensedUsersBox.tsx

@@ -21,20 +21,33 @@ const RightColumn = styled(StyledColumn)({
 const StyledButton = styled(Button)(({ theme }) => ({
     fontSize: theme.spacing(1.75),
     textDecoration: 'underline',
+    textAlign: 'right',
     '&:hover': {
         backgroundColor: theme.palette.background.paper,
     },
     fontWeight: theme.typography.h4.fontWeight,
 }));
 
+const InvisibleParagraph = styled('p')({
+    display: 'contents',
+});
+
 export const LicensedUsersBox = () => {
     return (
         <StyledContainer>
             <StyledColumn>
-                <Typography variant='body1' fontWeight='bold'>
+                <InvisibleParagraph>
-                    11/25
+                    <Typography
-                </Typography>
+                        variant='body1'
-                <Typography variant='body2'>Seats used last 30 days</Typography>
+                        fontWeight='bold'
+                        component='span'
+                    >
+                        11/25
+                    </Typography>
+                    <Typography variant='body2' component='span'>
+                        Seats used last 30 days
+                    </Typography>
+                </InvisibleParagraph>
             </StyledColumn>
             <RightColumn>
                 <HelpIcon

frontend/src/component/admin/users/UsersHeader/UsersHeader.tsx

@@ -29,7 +29,7 @@ const StyledElement = styled(Box)(({ theme }) => ({
 export const UsersHeader = () => {
     const licensedUsers = useUiFlag('licensedUsers');
     const { isOss } = useUiConfig();
-    const licensedUsersEnabled = licensedUsers && isOss();
+    const licensedUsersEnabled = licensedUsers && !isOss();
 
     return (
         <StyledContainer licensedUsersEnabled={licensedUsersEnabled}>