Removes max heap size setting used for build

Limiting the heap to 1G is suspect of causing excessive GC work which
 leads to failed tests, especially in large cluster HA ITs. Removing
 it seems to have no downsides so it is considered a good attempt at
 fixing the random test failures we see.

pom.xml

@@ -32,7 +32,7 @@
     <bouncycastle.version>1.52</bouncycastle.version>
     <generate-config-docs-phase>prepare-package</generate-config-docs-phase>
     <hsqldb.version>2.3.2</hsqldb.version>
-    <test.runner.jvm.settings>-Xmx1G -XX:MaxPermSize=128M -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=target/test-data -Dorg.neo4j.unsafe.impl.internal.dragons.UnsafeUtil.DIRTY_MEMORY=true -XX:-OmitStackTraceInFastThrow</test.runner.jvm.settings>
+    <test.runner.jvm.settings>-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=target/test-data -Dorg.neo4j.unsafe.impl.internal.dragons.UnsafeUtil.DIRTY_MEMORY=true -XX:-OmitStackTraceInFastThrow</test.runner.jvm.settings>
     <doclint-groups>reference</doclint-groups>
   </properties>