[chore] Skip flaky test on Windows

[pjanotti]

Description:
Since receiver/googlecloudspanner is unmaintained I'm opting to simply skip the flaky test on Windows.

Link to tracking Issue:
Workaround for #32397

Testing:
N/A

Documentation:
N/A

[crobert-1]

I entirely agree skipping is the right move for now. Slight nit though, I might leave the original issue open in the case of this component finding a maintainer. While we have the component in contrib it makes sense to keep its issues. If we get to the point of removing it we can go through and close all related issues 👍

If that's agreeable, we can remove the Fix prefix before the issue number in the PR description.

[crobert-1]

Another test in the same file failed on Windows:

itemcardinality_test.go:199: 
        	Error Trace:	D:/a/opentelemetry-collector-contrib/opentelemetry-collector-contrib/receiver/googlecloudspannerreceiver/internal/filter/itemcardinality_test.go:199
        	Error:      	"[0xc000089800 0xc000089[83](https://github.com/open-telemetry/opentelemetry-collector-contrib/actions/runs/10946967052/job/30394655819#step:8:84)0 0xc000089860]" should have 4 item(s), but has 3
        	Test:       	TestItemCardinalityFilter_FilterItems

We can add a skip now or later, whatever's easier

[pjanotti]

@crobert-1 let me add the skip for TestItemCardinalityFilter_FilterItems now. If others pop up I will feel tempted to use a build tag to skip all tests in Windows.