ci: Fix test race condition

[noahsmartin]

I saw this timeout in CI

#skip-changelog

[codecov]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
31314	2	31312	97

View the top 2 failed test(s) by shortest run time

SentryTests.SentryHttpTransportFlushIntegrationTests::testFlush_CalledMultipleTimes_ImmediatelyReturnsFalse

Stack Traces | 0s run time

.../SentryTests/Networking/SentryHttpTransportFlushIntegrationTests.swift:106 - XCTAssertEqual failed: ("SentryFlushResult(rawValue: 1)") is not equal to ("SentryFlushResult(rawValue: 0)")

SentryTracerTests::testConcurrentTransactions_OnlyOneGetsMeasurement

Stack Traces | 0s run time

Restarting after unexpected exit, crash, or test timeout in SentryTracerTests.testConcurrentTransactions_OnlyOneGetsMeasurement(); summary will include totals from previous launches.

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[itaybre]

Example timeout: https://github.com/getsentry/sentry-cocoa/actions/runs/16597578417/job/46948104948

[philipphofmann]

Thanks.