IMPALA-10771: Add Tencent COS support

This patch adds support for COS(Cloud Object Storage). Using the
hadoop-cos, the implementation is similar to other remote FileSystems.

New flags for COS:
- num_cos_io_threads: Number of COS I/O threads. Defaults to be 16.

Follow-up:
- Support for caching COS file handles will be addressed in
   IMPALA-10772.
- test_concurrent_inserts and test_failing_inserts in
   test_acid_stress.py are skipped due to slow file listing on
   COS (IMPALA-10773).

Tests:
 - Upload hdfs test data to a COS bucket. Modify all locations in HMS
   DB to point to the COS bucket. Remove some hdfs caching params.
   Run CORE tests.

Change-Id: Idce135a7591d1b4c74425e365525be3086a39821
Reviewed-on: http://gerrit.cloudera.org:8080/17503
Reviewed-by: Joe McDonnell <joemcdonnell@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>

tests/custom_cluster/test_topic_update_frequency.py

@@ -15,11 +15,12 @@ import pytest
 import time
 
 from tests.common.custom_cluster_test_suite import CustomClusterTestSuite
-from tests.common.skip import SkipIfS3, SkipIfGCS
+from tests.common.skip import SkipIfS3, SkipIfGCS, SkipIfCOS
 
 
 @SkipIfS3.variable_listing_times
 @SkipIfGCS.variable_listing_times
+@SkipIfCOS.variable_listing_times
 class TestTopicUpdateFrequency(CustomClusterTestSuite):
 
   @pytest.mark.execute_serially