fix(inputs.sqlserver): fixing wrong filtering for sqlAzureMIRequests and sqlAzureDBRequests

[deweter]

• Updated associated README.md.
• Wrote appropriate unit tests.
• Pull request title or commits are in conventional commit format

PR #10553 for an issue #10741 introduced a wrong filtering which leads to the state that all sessions are shown in the output - disregarding if they are running requests or not.

The filtering condition:
[request_id] IS NOT NULL --A request must exists
couldn't be ever true as in the previous code the [request_id] has been already changed to NonNullable inside the inner query:
NULLIF(r.[blocking_session_id],0) AS [blocking_session_id]

[powersj]

@Trovalo thoughts?

[deweter]

Just adding that this is a sample of the fixed output:

Only sessions which have a requests are shown (plus blocker SPIDs if present)

At this moment - before this fix - all sessions are shown - even when they have no request at all:

[Trovalo]

I'll have a look at it soon

[Trovalo]

@deweter thanks for noticing the issue, It's definitely an error that slipped through.
The very same issue is also valid for AzureSqlDb, (ref), can you apply the same fix in that query?

The issue is not present for SQL Server on-prem.

[telegraf-tiger]

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[Trovalo]

Thanks,@deweter.

@powersj can you approve/merge this?

[powersj]

Thank you both for the PR and the review!