Fix Util.constructHostname bug with us-west-2 region #3588

Job	Run time
Build	51s
Tests on Ubuntu (AWS, 18.x)	8s
Tests on Ubuntu (AWS, 20.x)	4s
Tests on Linux (nodejs-centos7-node14, AWS)	4s
Tests on Windows (AWS, 14.x)	1m 8s
Tests on Ubuntu (AZURE, 18.x)	6s
Tests on Linux (nodejs-centos7-node14, AZURE)	7s
Tests on Mac (AWS, 14.x)	1m 59s
Tests on Windows (AWS, 16.x)	53s
Tests on Ubuntu (AZURE, 20.x)	5s
Tests on Linux (nodejs-centos7-node14, GCP)	4s
Tests on Mac (AWS, 16.x)	1m 0s
Tests on Windows (AWS, 18.x)	55s
Tests on Ubuntu (GCP, 18.x)	7s
Tests on Linux (nodejs-centos7-fips, AWS)	4s
Tests on Mac (AWS, 18.x)	1m 32s
Tests on Windows (AWS, 20.x)	52s
Tests on Ubuntu (GCP, 20.x)	5s
Tests on Mac (AWS, 20.x)	1m 33s
Tests on Linux (nodejs-centos7-fips, AZURE)	6s
Tests on Windows (AZURE, 14.x)	55s
Tests on Mac (AZURE, 14.x)	1m 40s
Tests on Linux (nodejs-centos7-fips, GCP)	3m 16s
Tests on Windows (AZURE, 16.x)	59s
Tests on Mac (AZURE, 16.x)	1m 5s
Tests on Windows (AZURE, 18.x)	41s
Tests on Mac (AZURE, 18.x)	1m 13s
Tests on Windows (AZURE, 20.x)	42s
Tests on Mac (AZURE, 20.x)	1m 9s
Tests on Windows (GCP, 14.x)	52s
Tests on Mac (GCP, 14.x)	2m 10s
Tests on Windows (GCP, 16.x)	1m 13s
Tests on Mac (GCP, 16.x)	1m 29s
Tests on Windows (GCP, 18.x)	56s
Tests on Mac (GCP, 18.x)	1m 17s
Tests on Windows (GCP, 20.x)	1m 16s
Tests on Mac (GCP, 20.x)	1m 29s
	34m 5s

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