Disable flaky test (x-pack.metricbeat.module.sql.query.test_sql_oracle.Test)

[faec]

x-pack.metricbeat.module.sql.query.test_sql_oracle.Test is broken (#34993) and a PR was submitted to disable it last week (#35030) however it's still running and failing on active PRs, presumably because the @unittest.skip directives didn't stack correctly in the unittest api. This PR removes the conflicting directive so the test will be skipped for real.

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @faec? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2023-04-13T20:28:09.313+0000

• Duration: 53 min 24 sec

Test stats 🧪

Test	Results
Failed	0
Passed	1409
Skipped	95
Total	1504

💚 Flaky test report

Tests succeeded.

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