ci: Re-enable test aggregateQueryInATransactionShouldLockTheCountedDocuments

[dconeybe]

The test aggregateQueryInATransactionShouldLockTheCountedDocuments was disabled in #1040 because it failed when running against production.

java.lang.AssertionError: expected java.util.concurrent.ExecutionException to be thrown, but nothing was thrown
	at com.google.cloud.firestore.ITQueryCountTest.aggregateQueryInATransactionShouldLockTheCountedDocuments(ITQueryCountTest.java:238)

I need to check if this is a bug in the backend or a faulty test. This test passes against the Firestore emulator.

Here is the line in the test that is failing:

java-firestore/google-cloud-firestore/src/test/java/com/google/cloud/firestore/ITQueryCountTest.java

Line 238 in a7e90dd

executionException = assertThrows(ExecutionException.class, documentSetTask::get);

I've opened b/248152832 to investigate.

Once the issue is fixed, merge this PR to re-enable the test.