6 files declare their use of PerformanceTestBase

AssetAggregationAcrossPagesTest.php in core/profiles/demo_umami/tests/src/FunctionalJavascript/AssetAggregationAcrossPagesTest.php
OpenTelemetryAuthenticatedPerformanceTest.php in core/profiles/demo_umami/tests/src/FunctionalJavascript/OpenTelemetryAuthenticatedPerformanceTest.php
OpenTelemetryFrontPagePerformanceTest.php in core/profiles/demo_umami/tests/src/FunctionalJavascript/OpenTelemetryFrontPagePerformanceTest.php
OpenTelemetryNodePagePerformanceTest.php in core/profiles/demo_umami/tests/src/FunctionalJavascript/OpenTelemetryNodePagePerformanceTest.php
PerformanceTest.php in core/profiles/demo_umami/tests/src/FunctionalJavascript/PerformanceTest.php
StandardPerformanceTest.php in core/profiles/standard/tests/src/FunctionalJavascript/StandardPerformanceTest.php

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