Update our preferred models

[dkotter]

What?

Updates the preferred Anthropic text and vision model from claude-sonnet-4-6 to claude-sonnet-5, the preferred Google text and vision model from gemini-3-flash-preview to gemini-3.6-flash and the preferred OpenAI text and vision model from gpt-5.4-mini to gpt-5.6-luna and removes the setting of custom temperature parameters.

Why?

We want to ensure the default models we recommend are using the latest versions of models. In addition, the OpenAI GPT-5.5+ models don't support setting temperature values unless reasoning mode is turned off. There are a few different approaches we could take here:

1. Remove the setting of temperature values (what this PR does)
2. Set reasoning effort to none but will need to ensure we only apply this to OpenAI models
3. Update the OpenAI provider to ignore temperature values if the model doesn't support it

For now I've gone with option 1 in this PR as I don't think setting temperature really provides any value but open to thoughts there.

How?

Updates our preferred models for Anthropic, Google and OpenAI to be the latest versions and removes anywhere we were using using_temperature on the prompt builder

Use of AI Tools

None

Testing Instructions

One by one, configure Anthropic, Google and OpenAI and test all features to ensure they still work

Changelog Entry

Changed - Updated preferred models to more recent ones for the three default providers.
Deprecated - Filter wpai_meta_description_result_temperature is no longer being used and will be removed in the next release.
Removed - No longer set custom temperature values on any of our requests.

[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.41%. Comparing base (7976907) to head (4b0e875).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop     #913      +/-   ##
=============================================
- Coverage      80.43%   80.41%   -0.03%     
  Complexity      2565     2565              
=============================================
  Files            110      110              
  Lines          10448    10437      -11     
=============================================
- Hits            8404     8393      -11     
  Misses          2044     2044              

Flag	Coverage Δ
unit	80.41% <100.00%> (-0.03%)	⬇️

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