Add tablet compaction score metrics (#2427)

[Metric] Add tablet compaction score metrics

Backend:
    Add metric "tablet_max_compaction_score" to monitor the current max compaction
    score of tablets on this Backend. This metric will be updated each time
    the compaction thread picking tablets to compact.

Frontend:
    Add metric "tablet_max_compaction_score" for each Backend. These metrics will
    be updated when backends report tablet.
    And also add a calculated metric "max_tablet_compaction_core" to monitor the
    max compaction core of tablets on all Backends.

fe/src/test/java/org/apache/doris/catalog/BackendTest.java

@@ -75,7 +75,7 @@ public class BackendTest {
         backend.updateOnce(bePort, httpPort, beRpcPort);
 
         PowerMock.mockStatic(MetricRepo.class);
-        MetricRepo.generateTabletNumMetrics();
+        MetricRepo.generateBackendsTabletMetrics();
         EasyMock.expectLastCall().anyTimes();
         PowerMock.replay(MetricRepo.class);
     }