fix: resolve OAuth installation store bugs and typos

[WilliamBergamin]

Summary

• Fix KeyError in AsyncCacheableInstallationStore.async_delete_bot when deleting a bot that isn't cached (aligns with sync version's guard)
• Fix incorrect error messages in S3 delete_bot/delete_installation that said "Failed to find bot installation data" instead of "Failed to delete"
• Fix typo "absense" → "absence" in log messages across file, S3, and SQLite3 installation stores

Testing

CI coverage should be sufficient

Category

• slack_sdk.web.WebClient (sync/async) (Web API client)
• slack_sdk.webhook.WebhookClient (sync/async) (Incoming Webhook, response_url sender)
• slack_sdk.socket_mode (Socket Mode client)
• slack_sdk.signature (Request Signature Verifier)
• slack_sdk.oauth (OAuth Flow Utilities)
• slack_sdk.models (UI component builders)
• slack_sdk.scim (SCIM API client)
• slack_sdk.audit_logs (Audit Logs API client)
• slack_sdk.rtm_v2 (RTM client)
• /docs (Documents)
• /tutorial (PythOnBoardingBot tutorial)
• tests/integration_tests (Automated tests for this library)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run python3 -m venv .venv && source .venv/bin/activate && ./scripts/run_validation.sh after making the changes.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.97%. Comparing base (df39bee) to head (42603cb).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...sdk/oauth/installation_store/amazon_s3/__init__.py	20.00%	4 Missing ⚠️
...lation_store/async_cacheable_installation_store.py	0.00%	2 Missing ⚠️

❌ Your patch status has failed because the patch coverage (33.33%) is below the target coverage (50.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@ Coverage Diff @@## main #1864 +/- ##
==========================================
- Coverage 84.01% 83.97% -0.04% 
==========================================
Files 117 117 Lines 13256 13257 +1 ==========================================
- Hits 11137 11133 -4 - Misses 2119 2124 +5 

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[zimeg]

@WilliamBergamin LGTM but before merging might the PR title describe the guarded cache removal more?

[WilliamBergamin]

@zimeg good catch my PR title changed due to follow up commits