Lower threshold even more for SIFTFast to make the test pass on raoul

Summary

Update threshold for SIFTFast test to make this last failing test green: https://dash.orfeo-toolbox.org/testDetails.php?test=99045451&build=350210

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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Check before merging:

• All discussions are resolved
• At least 2 votes from core developers, no vote.
• The feature branch is (reasonably) up-to-date with the base branch
• Dashboard is green
• Copyright owner has signed the ORFEO ToolBox Contributor License Agreement