HDDS-9377. Call MutableStat.add(long x) method as a runnable task in a separate service executor

[juncevich]

What changes were proposed in this pull request?

Change synchronized metrics collect methods to read/write lock implementation.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-9377

How was this patch tested?

I wrote the JUnit test (I'm not sure I should add this test to this PR) to compare performance metric realization.

  @RepeatedTest(100)
  void testMyMetrics() throws InterruptedException {
    OzoneMutableRate rate = new OzoneMutableRate("Test name", "Test description", true);
    final MetricsRecordBuilder builder = getMetricsRecordBuilder();
    ExecutorService executor = Executors.newFixedThreadPool(10);
    for (int i = 0; i < 100; i++) {
      int finalI = i;

      executor.submit(() -> {
        rate.add(finalI);
        if (finalI % 100 == 0) {
          rate.snapshot(getMetricsRecordBuilder());
        }
      });
    }
    executor.awaitTermination(1, TimeUnit.SECONDS);
    rate.snapshot(builder);
    assertEquals(100, builder.metrics().get(0).value().intValue());
  }