Editing a custom model and saving it still shows up when trying to add a new model

[srirambv]

Description

Editing a custom model and saving it still shows up when trying to add a new model

Steps to reproduce

1. Add a custom model
2. Edit the model
3. Click on Save changes to close edit screen
4. Click on Add model
5. Shows Edit model screen with prefilled info
6. Click on Close
7. Edit existing model
8. Close on the edit model screen
9. Click on Add model, shows screen for Adding a new model

Actual result

Add-Edit.model.mp4

Expected result

Add model should always show the add new model irrespective of how the edit model screen is closed either by Save or Close

Reproduces how often

Easily reproduced

Brave version (brave://version info)

Brave	1.71.102 Chromium: 129.0.6668.70 (Official Build) beta (64-bit)
Revision	d901535b1091c5f39eb2b5426b8fa8e7f3c5edf0
OS	Windows 11 Version 23H2 (Build 22631.4169)

Channel information

• release (stable)
• beta
• nightly

Reproducibility

• with Brave Shields disabled
• with Brave Rewards disabled
• in the latest version of Chrome

Miscellaneous information

cc: @rebron @darkdh @mattmcalister @brave/qa-team

[aguscruiz]

I think it'll be a better experience if we do it like in my design where adding/editing a model happens in a new page. It'll be an even better experience once we add more options to the advanced settings like we're planning to.

cc @petemill @LorenzoMinto

Design:
https://www.figma.com/design/m0Gdbf0wtqyfEFGm32VLLc/%F0%9F%94%84-Leo-%5BIN-PROGRESS%5D?node-id=3249-1029&t=Q9SIskItAPqJtDyF-1

Advanced options mock:
https://www.figma.com/design/m0Gdbf0wtqyfEFGm32VLLc/%F0%9F%94%84-Leo-%5BIN-PROGRESS%5D?node-id=5242-36725&t=Q9SIskItAPqJtDyF-1

[mattmcalister]

@aguscruiz agreed, although maybe @jonathansampson can fix this little bug for now...?