migration_performance_tuning/parallel: disable test on s390x

[smitterl]

Our systems migrate too fast with 100 parallel connections. I was only able to slow things down sufficiently with 50 connections and bandwidth 5 to get the test pass but handling this is easily doable via config for just the specific test case

migration.migration_performance_tuning.migration_parallel_connections.unix.conn_num_100.with_precopy.p2p

Let's disable this one on s390x, so our system picks up the other tests for coverage.

Summary by CodeRabbit

• Chores
  • Updated test configuration for migration performance scenarios to refine test variant behavior.

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[coderabbitai]

Walkthrough

A single-line directive "no s390-virtio" is added to the conn_num_100 variant within the default_conn_num test case in the migration parallel connections configuration file. This directive excludes the s390-virtio architecture path for that specific test variant configuration.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: disabling a specific test on s390x architecture due to performance tuning constraints.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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