Replace Llama 2 with Llama 3 as an AI model

[I-I-IT]

This seems obvious, but haven't seem an issue about adding the new more accurate and more responsive Meta Llama 3 8b as a the unlimited model to replace Llama 2 13b. Llama 3 8b is better than even Llama 2 70b, according to Arena LMSYS leaderboard<

Test plan

All llama2 strings now use llama3. Query functionality still works with the llama model selection.

[mattmcalister]

Thanks @TechFanTheo . It is indeed coming and we need an issue for it.

[kjozwiak]

The above requires 1.67.105 or higher for 1.67.x verification 👍

[I-I-IT]

I have latest Nightly and tested it. Says Connection error with Llama 3 but it works fine with other models.

Did you enable the Llama 3 servers yet ?

[I-I-IT]

Fixed.

[stephendonner]

Verification PASSED using

Brave | 1.67.107 Chromium: 126.0.6478.26 (Official Build) beta (x86_64)
-- | --
Revision | 2831369c7540d93e98f38d9b463f6762430a7982
OS | macOS Version 11.7.10 (Build 20G1427)

Steps:

1. installed 1.67.107
2. launched Brave
3. chose Llama 3 8b for Default model for new conversations in brave://settings/leo-assistant
4. loaded https://www.vox.com/technology/352849/openai-chatgpt-google-meta-artificial-intelligence-vox-media-chatbots
5. clicked on Leo in the sidebar panel
6. clicked on Summarize this page
7. clicked I understand
8. waited
9. also clicked on Suggest questions...
10. confirmed questions loaded

Confirmed Llama 3 8b correctly/quickly summarized the page contents and rendered/answered Suggest questions... as well

example	example	example	example	example	example	example

[Uni-verse]

Verified on Samsung Galaxy S21 using the following version:

Brave	1.67.112 Chromium: 126.0.6478.40 (Official Build) (64-bit) 
Revision	4190f7ced064ec338b9dedc915d70b50e28c843e
OS	Android 13; Build/TP1A.220624.014; 33; REL

• Ensured Llama 3 8b has replaced Llama 2 in the language models menu for new and existing users.
• Ensured Llama model is updated in the Default model in Advanced Settings
• Ensured query functionality with and without page context for free and premium users.
• Ensured model is not rate limited.
• Ensured users upgrading with Llama 2 set as default will default to Llama 3.
• Ensured summarize this page and suggestions are working with Llama.
• Ensured Ask Leo is working with Llama 3 from the omnibox.

Example	Example	Example	Example

[kjozwiak]

The above requires 1.67.121 or higher for 1.67.x verification on iOS 👍 CCing @hffvld @Uni-verse