[8.1] systemtest: don't use fleet-server IP (backport #7157)

[mergify]

This is an automatic backport of pull request #7157 done by Mergify.

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• Reason: null

• Start Time: 2022-02-01T15:26:41.176+0000

• Duration: 62 min 57 sec

• Commit: 46443e7

Test stats 🧪

Test	Results
Failed	0
Passed	5625
Skipped	20
Total	5645

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