Relax Testcontainers parallelism limit from 1 to 2 (#12034)

Relaxed test containers hard limit of one.

Merge branch 'master' into alexeyk/test-containers-limit-2

Make Testcontainers parallelism limit configurable via Gradle property

Read maxParallelUsages from the testcontainersMaxParallelUsages Gradle
property (default 2) so it can be tuned in CI or locally without a code
change, per review feedback.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: alexey.kuznetsov <alexey.kuznetsov@datadoghq.com>

Author: AlexeyKuznetsov-DD

gradle.properties

@@ -5,4 +5,9 @@ org.gradle.jvmargs=-XX:MaxMetaspaceSize=1g
 # Toggle on to get more details during IJ sync
 #org.gradle.logging.level=info
 
+# Max number of Testcontainers-backed test tasks allowed to run concurrently.
+# Override in CI or locally to trade CI throughput against resource pressure
+# (containers, memory, ports), e.g. -PtestcontainersMaxParallelUsages=3
+testcontainersMaxParallelUsages=2
+
 # CI use constrained org.gradle.java.installations settings

gradle/java_no_deps.gradle

@@ -147,7 +147,7 @@ abstract class TestcontainersLimitService implements BuildService<BuildServicePa
 }
 
 ext.testcontainersLimit = gradle.sharedServices.registerIfAbsent("testcontainersLimit", TestcontainersLimitService) {
-  maxParallelUsages = 1
+  maxParallelUsages = project.findProperty("testcontainersMaxParallelUsages").toInteger()
 }
 
 // Task for tests that want to run forked in their own separate JVM