metrics: Fix `Metrics should have the correct labels` test

[zeeke]

sriov_kubepoddevice metric might end up in the Prometheus database after a while, as the default scrape interval is 30s. This leads to failures in the end-to-end lane like:

[sriov] Metrics Exporter When Prometheus operator is available [It] Metrics should have the correct labels
/root/opr-ocp2-1/data/sriov-network-operator/sriov-network-operator/test/conformance/tests/test_exporter_metrics.go:132

  [FAILED] no value for metric sriov_kubepoddevice

Put the metric assertion in an Eventually statement

[github-actions[bot]]

Thanks for your PR, To run vendors CIs, Maintainers can use one of:

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  To skip the vendors CIs, Maintainers can use one of:

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[coveralls]

Pull Request Test Coverage Report for Build 11229233629

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.04%) to 45.136%

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Files with Coverage Reduction	New Missed Lines	%
controllers/drain_controller.go	1	68.06%
controllers/generic_network_controller.go	5	74.38%
<!--	Total:	6		-->

Totals
Change from base Build 11212485228:	-0.04%
Covered Lines:	6658
Relevant Lines:	14751

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💛 - Coveralls