chore: update C++ server-side SDK Redis Source from 2.1.19 to 2.2.2

[kinyoklion]

Summary

Updates the C++ Server-side SDK Redis Source dependency used in CI from 2.1.19 to 2.2.2 in .github/variables/cpp-sdk-versions.env.

Notable changes in the Redis Source between these versions:

• 2.2.0: Updated to hiredis 1.3
• 2.2.2: Bumped internal C++ server SDK dependency to 3.10.1

The primary C++ Server SDK dependency (sdk=3.10.1) is already at the latest stable version.

Link to Devin session: https://app.devin.ai/sessions/6147113664cc4bd6bf0d1aff7d50fbda
Requested by: @kinyoklion

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment, CI, and merge conflict monitoring