Build: Run tests against Spark 3.0 and Spark 3.1

[RussellSpitzer]

Due to an issue with the build.gradle both the spark test and test31 modules were both running with Spark 3.1. Removing the inter dependency fixes the issue and both grade tasks now run with the correct respective spark versions.

@cwsteinbach

[RussellSpitzer]

@rdblue - @karuppayya noticed this when we were debugging the issue for #2783

[RussellSpitzer]

➜  iceberg-master git:(FixBuildAgainstSparkVersions) ✗ g check --dry-run | grep testSpark31
:iceberg-spark3:testSpark31 SKIPPED
:iceberg-spark3-extensions:testSpark31 SKIPPED

➜  iceberg-master git:(FixBuildAgainstSparkVersions) ✗ g :iceberg-spark3:dependencies --configuration compileOnly | grep spark-hive
\--- org.apache.spark:spark-hive_2.12:3.0.3
➜  iceberg-master git:(FixBuildAgainstSparkVersions) ✗ g :iceberg-spark3:dependencies --configuration testRuntimeClasspath | grep spark-hive
+--- org.apache.spark:spark-hive_2.12:3.0.3


// Only compiles tests
➜  iceberg-master git:(FixBuildAgainstSparkVersions) ✗ g :iceberg-spark3:dependencies --configuration spark31CompileClasspath | grep spark-hive
+--- org.apache.spark:spark-hive_2.12:3.0.3 -> 3.1.1
+--- org.apache.spark:spark-hive_2.12:3.1.1 (*)
➜  iceberg-master git:(FixBuildAgainstSparkVersions) ✗ g :iceberg-spark3:dependencies --configuration spark31RuntimeClasspath | grep spark-hive
+--- org.apache.spark:spark-hive_2.12:3.0.3 -> 3.1.1
+--- org.apache.spark:spark-hive_2.12:3.1.1 (*)

[RussellSpitzer]

Had to make an additional change to trigger both sets of tests to run during gradle check command, rerunning suite