Compile Nomulus with Java 21 (#2344)

Make the necessary changes for the code base to compile with JDK 21.

Other changes:

1. Upgraded testcontainer version and the SQL image version (to be the
   same as what we use in Cloud SQL). This led to some schema changes and
   also changed the order of results in some test queries (for the
   better I think, as the new order appears to be alphabetical).
2. Remove dependency on Truth8, which is deprecated.
3. Enable parallel Gradle task execution and greatly increased the
   number of parallel tests in standardTest. Removed outcastTest.

java_common.gradle

@@ -88,6 +88,7 @@ test {
 //
 // A typical use case is to run tests from desktop that accesses Cloud resources.
 tasks.withType(Test).configureEach {
+  maxHeapSize = "4096m"
   def gcp_integration_env_property = 'test.gcp_integration.env'
 
   if (project.hasProperty(gcp_integration_env_property)) {