remove compiler warnings about unqualified calls to yield() (#16995)

processing/src/test/java/org/apache/druid/common/guava/CombiningSequenceTest.java

@@ -294,7 +294,7 @@ public class CombiningSequenceTest
           {
             count++;
             if (count % yieldEvery == 0) {
-              yield();
+              this.yield();
             }
             return rhs;
           }

processing/src/test/java/org/apache/druid/common/guava/ComplexSequenceTest.java

@@ -71,7 +71,7 @@ public class ComplexSequenceTest
           @Override
           public Integer accumulate(Integer accumulated, Integer in)
           {
-            yield();
+            this.yield();
             return in;
           }
         }

processing/src/test/java/org/apache/druid/java/util/common/guava/ConcatSequenceTest.java

@@ -263,7 +263,7 @@ public class ConcatSequenceTest
           @Override
           public Integer accumulate(Integer accumulated, Integer in)
           {
-            yield();
+            this.yield();
             return in;
           }
         }

processing/src/test/java/org/apache/druid/java/util/common/guava/LimitedSequenceTest.java

@@ -104,7 +104,7 @@ public class LimitedSequenceTest
               public OutType accumulate(OutType accumulated, Integer in)
               {
                 final OutType retVal = super.accumulate(accumulated, in);
-                yield();
+                this.yield();
                 return retVal;
               }
             }

processing/src/test/java/org/apache/druid/java/util/common/guava/SequenceTestHelper.java

@@ -65,7 +65,7 @@ public class SequenceTestHelper
           {
             if (++count >= numToTake) {
               count = 0;
-              yield();
+              this.yield();
             }
 
             Assert.assertEquals(prefix, valsIter.next(), in);

processing/src/test/java/org/apache/druid/java/util/common/guava/SkippingSequenceTest.java

@@ -110,7 +110,7 @@ public class SkippingSequenceTest
               public OutType accumulate(OutType accumulated, Integer in)
               {
                 final OutType retVal = super.accumulate(accumulated, in);
-                yield();
+                this.yield();
                 return retVal;
               }
             }

processing/src/test/java/org/apache/druid/query/aggregation/AggregationTestHelper.java

@@ -757,7 +757,7 @@ public class AggregationTestHelper implements Closeable
                 @Override
                 public Object accumulate(Object accumulated, Object in)
                 {
-                  yield();
+                  this.yield();
                   return in;
                 }
               }