PruneTableScanColumns throws an exception when column name contains only non-alphanumeric

[ebyhr]

This issue happened after the last commit of #21204 (SymbolAllocator change)

The following test fail on Hive connector:

    @Test
    public void testColumnName()
    {
        try (TestTable table = new TestTable(getQueryRunner()::execute, "test_name", "AS SELECT 1 \"あ\"")) {
            assertQuery("SELECT * FROM " + table.getName(), "VALUES (1)");
        }
    }

java.lang.IllegalArgumentException: name is empty
	at io.trino.spi.expression.Variable.<init>(Variable.java:35)
	at io.trino.sql.planner.iterative.rule.PruneTableScanColumns.lambda$pruneColumns$0(PruneTableScanColumns.java:75)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:212)
	at java.base/java.util.Collections$2.tryAdvance(Collections.java:5074)
	at java.base/java.util.Collections$2.forEachRemaining(Collections.java:5082)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:556)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:546)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:265)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:702)
	at io.trino.sql.planner.iterative.rule.PruneTableScanColumns.pruneColumns(PruneTableScanColumns.java:76)
	at io.trino.sql.planner.iterative.rule.PruneTableScanColumns.pushDownProjectOff(PruneTableScanColumns.java:63)
	at io.trino.sql.planner.iterative.rule.PruneTableScanColumns.pushDownProjectOff(PruneTableScanColumns.java:48)
	at io.trino.sql.planner.iterative.rule.ProjectOffPushDownRule.lambda$apply$0(ProjectOffPushDownRule.java:63)
	at java.base/java.util.Optional.flatMap(Optional.java:289)
	at io.trino.sql.planner.iterative.rule.ProjectOffPushDownRule.apply(ProjectOffPushDownRule.java:63)
	at io.trino.sql.planner.iterative.rule.ProjectOffPushDownRule.apply(ProjectOffPushDownRule.java:38)
	at io.trino.sql.planner.iterative.IterativeOptimizer.transform(IterativeOptimizer.java:216)
	at io.trino.sql.planner.iterative.IterativeOptimizer.exploreNode(IterativeOptimizer.java:181)
	at io.trino.sql.planner.iterative.IterativeOptimizer.exploreGroup(IterativeOptimizer.java:144)
	at io.trino.sql.planner.iterative.IterativeOptimizer.exploreChildren(IterativeOptimizer.java:264)
	at io.trino.sql.planner.iterative.IterativeOptimizer.exploreGroup(IterativeOptimizer.java:146)
	at io.trino.sql.planner.iterative.IterativeOptimizer.optimizeAndMarkPlanChanges(IterativeOptimizer.java:129)
	at io.trino.sql.planner.optimizations.AdaptivePlanOptimizer.optimize(AdaptivePlanOptimizer.java:33)
	at io.trino.sql.planner.LogicalPlanner.runOptimizer(LogicalPlanner.java:301)
	at io.trino.sql.planner.LogicalPlanner.plan(LogicalPlanner.java:264)
	at io.trino.sql.planner.LogicalPlanner.plan(LogicalPlanner.java:236)
	at io.trino.sql.planner.LogicalPlanner.plan(LogicalPlanner.java:231)
	at io.trino.execution.SqlQueryExecution.doPlanQuery(SqlQueryExecution.java:498)
	at io.trino.execution.SqlQueryExecution.planQuery(SqlQueryExecution.java:478)
	at io.trino.execution.SqlQueryExecution.start(SqlQueryExecution.java:416)
	at io.trino.execution.SqlQueryManager.createQuery(SqlQueryManager.java:272)
	at io.trino.dispatcher.LocalDispatchQuery.startExecution(LocalDispatchQuery.java:145)
	at io.trino.dispatcher.LocalDispatchQuery.lambda$waitForMinimumWorkers$2(LocalDispatchQuery.java:129)
	at io.airlift.concurrent.MoreFutures.lambda$addSuccessCallback$12(MoreFutures.java:570)
	at io.airlift.concurrent.MoreFutures$3.onSuccess(MoreFutures.java:545)
	at com.google.common.util.concurrent.Futures$CallbackListener.run(Futures.java:1137)
	at io.trino.$gen.Trino_testversion____20240509_062117_71.run(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at java.base/java.lang.Thread.run(Thread.java:1570)

[ebyhr]

cc: @martint @dain @findepi