[MacCatalyst] NavigationPage.BackButtonTitle is not visible when NavigationPage.TitleView is set on the pushed page

### Description

When a custom TitleView is applied to a pushed page using [NavigationPage.SetTitleView], the back button title set via [NavigationPage.SetBackButtonTitle] on the previous page is not displayed. The back button text is not visible correctly on Mac(version 26 ).

| Expected Output | Actual Output |
|-----------------|---------------|
| | |

### Steps to Reproduce

1. Run this sample on MacCatalyst 26 version [CustomBackButtonTitle.zip](https://github.com/user-attachments/files/27996772/CustomBackButtonTitle.zip)
2. Create a NavigationPage with a root ContentPage , Set NavigationPage.SetBackButtonTitle(this, "Main").
3. Push a new ContentPage and set NavigationPage.SetTitleView on it
4. Observe the back button — the title "Main" is not visible .

Expected Behavior:
The back button should display "Main" as the back button title text alongside the back arrow.

Actual Behavior:
The back button shows only the back arrow icon. The back button title text is not fully visible.

### Link to public reproduction project repository

_No response_

### Version with bug

10.0.60

### Is this a regression from previous behavior?

Not sure, did not test other versions

### Last version that worked well

_No response_

### Affected platforms

macOS

### Affected platform versions

_No response_

### Did you find any workaround?

_No response_

### Relevant log output

```shell

```

Start by running the attached CustomBackButtonTitle.zip sample on MacCatalyst 26 and reproduce the missing "Main" text after setting TitleView on the pushed page. Trace the NavigationPage.SetBackButtonTitle and NavigationPage.SetTitleView paths; done means the back arrow and "Main" title are both visible.

Written by the indexing model from the issue text.