Property to limit test parallelisation (airbytehq#23870)

* Adds new functionality on integration test pipeline and test pipeline in order to reduce parallelization.
It's done by creating a `gradle.properties` file in the connector root folder.

Extra: removes test concatenation for performance tests.

* rename parameter

* fix names

* Reduce threads

airbyte-integrations/connectors/destination-snowflake/gradle.properties

@@ -0,0 +1 @@
+numberThreads=2

build.gradle

@@ -342,6 +342,7 @@ subprojects { subproj ->
     // make tag accessible in submodules.
     ext {
         cloudStorageTestTagName = 'cloud-storage'
+        numberThreads = project.hasProperty('numberThreads') ? project.getProperty('numberThreads') : Runtime.runtime.availableProcessors() ?: 1
     }
 
     spotbugs {
@@ -354,7 +355,9 @@ subprojects { subproj ->
     }
 
     test {
-        maxParallelForks = Runtime.runtime.availableProcessors() ?: 1
+        //This allows to set up a `gradle.properties` file inside the connector folder to reduce number of threads and reduce parallelization.
+        //Specially useful for connectors that shares resources (like Redshift or Snowflake).
+        maxParallelForks = numberThreads
 
         jacoco {
             enabled = true

buildSrc/src/main/groovy/airbyte-integration-test-java.gradle

@@ -45,8 +45,11 @@ class AirbyteIntegrationTestJavaPlugin implements Plugin<Project> {
                 dependsOn project.airbyteDocker
             }
 
+            //This allows to set up a `gradle.properties` file inside the connector folder to reduce number of threads and reduce parallelization.
+            //Specially useful for connectors that shares resources (like Redshift or Snowflake).
+            ext.numberThreads = project.hasProperty('numberThreads') ? project.getProperty('numberThreads') : Runtime.runtime.availableProcessors() ?: 1
             maxHeapSize = '3g'
-            maxParallelForks = Runtime.runtime.availableProcessors() ?: 1
+            maxParallelForks = numberThreads
 
             // This is needed to make the destination-snowflake tests succeed - https://github.com/snowflakedb/snowflake-jdbc/issues/589#issuecomment-983944767
             jvmArgs = ["--add-opens=java.base/java.nio=ALL-UNNAMED"]

buildSrc/src/main/groovy/airbyte-performance-test-java.gradle

@@ -22,7 +22,7 @@ class AirbytePerformanceTestJavaPlugin implements Plugin<Project> {
         }
 
         project.task('performanceTestJava', type: Test) {
-            testClassesDirs += project.sourceSets.performanceTestJava.output.classesDirs
+            testClassesDirs = project.sourceSets.performanceTestJava.output.classesDirs
             classpath += project.sourceSets.performanceTestJava.runtimeClasspath
 
             systemProperty "cpuLimit", System.getProperty("cpuLimit")