fix: layout content width on large screens (#8267)

I believe the changes in #8234,
more specifically [this
change](https://github.com/Unleash/unleash/pull/8234/files#diff-3a5e0763fe1effa9cd485763fecf0633ce8f0877c9d1971e6bd5c5abe7426364L64),
have caused the main layout content to no longer stretch to its maximum
relative width on larger screens.

This adjustment seems to resolve this issue, ensuring proper behavior on
larger screens without introducing any overflow issues on smaller
screens.

frontend/src/component/layout/MainLayout/MainLayout.tsx

@@ -67,6 +67,9 @@ const NewMainLayoutContent = styled(Grid)(({ theme }) => ({
     margin: '0 auto',
     paddingLeft: theme.spacing(2),
     paddingRight: theme.spacing(2),
+    [theme.breakpoints.up(1856)]: {
+        width: '100%',
+    },
     [theme.breakpoints.down(1856)]: {
         marginLeft: theme.spacing(7),
         marginRight: theme.spacing(7),