Cap Mistral's context length at 2k

[collingray]

Description

Caps Mistral's context length at 2k, as its default length of 32k uses a very large amount of memory.

Discussed in #490 and #491

This change will not be needed after #493, and is just to allow for Mistral to be easily used in the short term while #493 is in review.

Fixes #490

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have not rewritten tests relating to key interfaces which would affect backward compatibility

[alan-cooney]

Yep thanks makes sense - approving now and we'll revert once we have the full fix