fix(custom-theme): Remove duplicate .customTheme selectors (@Leonabcd123) (monkeytypegame#7120)

### Description

Removed duplicate `.customTheme` selectors to make:

```
$(`.pageSettings .tabContent.customTheme #${color}[type='color']`).attr(
  "value"
)
```

Select the custom theme data inputs successfully.

Closes monkeytypegame#7121
Closes monkeytypegame#7122

Author: Leonabcd123

frontend/src/ts/modals/share-custom-theme.ts

@@ -30,9 +30,9 @@ async function generateUrl(): Promise<string> {
   } = {
     c: ThemeController.colorVars.map(
       (color) =>
-        $(
-          `.pageSettings .customTheme .tabContent.customTheme #${color}[type='color']`
-        ).attr("value") as string
+        $(`.pageSettings .tabContent.customTheme #${color}[type='color']`).attr(
+          "value"
+        ) as string
     ),
   };
 

frontend/src/ts/modals/simple-modals.ts

@@ -1133,7 +1133,7 @@ list.updateCustomTheme = new SimpleModal({
       for (const color of ThemeController.colorVars) {
         newColors.push(
           $(
-            `.pageSettings .customTheme .tabContent.customTheme #${color}[type='color']`
+            `.pageSettings .tabContent.customTheme #${color}[type='color']`
           ).attr("value") as string
         );
       }