Non-existed metric hiveClientCalls.count of CodeGenerator in Monitoring Doc

There is a duplicated `hiveClientCalls.count` metric in both `namespace=HiveExternalCatalog` and  `namespace=CodeGenerator` bullet lists of Spark Monitoring doc, but there is only one inside object HiveCatalogMetrics in source code.

• namespace=HiveExternalCatalog
  • note:: these metrics are conditional to a configuration parameter: spark.metrics.staticSources.enabled (default is true)
  • fileCacheHits.count
  • filesDiscovered.count
  • hiveClientCalls.count
  • parallelListingJobCount.count
  • partitionsFetched.count
• namespace=CodeGenerator
  • note:: these metrics are conditional to a configuration parameter: spark.metrics.staticSources.enabled (default is true)
  • compilationTime (histogram)
  • generatedClassSize (histogram)
  • generatedMethodSize (histogram)
  • hiveClientCalls.count
  • sourceCodeSize (histogram)