Fixing missing error message from pinot-admin command

[xiangfu0]

Fix the issue that pinot-admin.sh only return message for success request, not failed messages from http requests.

Current:

bin/pinot-admin.sh AddTable -tableConfigFile examples/baseballStats_offline_table_config.json -schemaFile examples/baseballStats_schema.json -controllerHost 127.0.0.1 -controllerPort 9000 -exec

Executing command: AddTable -tableConfigFile examples/baseballStats_offline_table_config.json -schemaFile examples/baseballStats_schema.json -controllerHost 127.0.0.1 -controllerPort 9000 -exec
Sending request: http://127.0.0.1:9000/schemas to controller: localhost, version: Unknown
Exception caught:
java.io.IOException: Server returned HTTP response code: 409 for URL: http://127.0.0.1:9000/tables
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1900) ~[?:1.8.0_232]
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1498) ~[?:1.8.0_232]
	at org.apache.pinot.tools.admin.command.AbstractBaseAdminCommand.sendRequest(AbstractBaseAdminCommand.java:85) ~[pinot-all-0.4.0-SNAPSHOT-jar-with-dependencies.jar:0.4.0-SNAPSHOT-80a943501464d983396ae935b1ca7061d94ade37]
	at org.apache.pinot.tools.admin.command.AbstractBaseAdminCommand.sendPostRequest(AbstractBaseAdminCommand.java:63) ~[pinot-all-0.4.0-SNAPSHOT-jar-with-dependencies.jar:0.4.0-SNAPSHOT-80a943501464d983396ae935b1ca7061d94ade37]
	at org.apache.pinot.tools.admin.command.AddTableCommand.sendTableCreationRequest(AddTableCommand.java:138) ~[pinot-all-0.4.0-SNAPSHOT-jar-with-dependencies.jar:0.4.0-SNAPSHOT-80a943501464d983396ae935b1ca7061d94ade37]
	at org.apache.pinot.tools.admin.command.AddTableCommand.execute(AddTableCommand.java:163) ~[pinot-all-0.4.0-SNAPSHOT-jar-with-dependencies.jar:0.4.0-SNAPSHOT-80a943501464d983396ae935b1ca7061d94ade37]
	at org.apache.pinot.tools.admin.PinotAdministrator.execute(PinotAdministrator.java:158) [pinot-all-0.4.0-SNAPSHOT-jar-with-dependencies.jar:0.4.0-SNAPSHOT-80a943501464d983396ae935b1ca7061d94ade37]
	at org.apache.pinot.tools.admin.PinotAdministrator.main(PinotAdministrator.java:170) [pinot-all-0.4.0-SNAPSHOT-jar-with-dependencies.jar:0.4.0-SNAPSHOT-80a943501464d983396ae935b1ca7061d94ade37]

After fix:

➜ bin/pinot-admin.sh AddTable -tableConfigFile examples/baseballStats_offline_table_config.json -schemaFile examples/baseballStats_schema.json -controllerHost 127.0.0.1 -controllerPort 9000 -exec

Executing command: AddTable -tableConfigFile examples/baseballStats_offline_table_config.json -schemaFile examples/baseballStats_schema.json -controllerHost 127.0.0.1 -controllerPort 9000 -exec
Sending request: http://127.0.0.1:9000/schemas to controller: localhost, version: Unknown
{"code":409,"error":"Table baseballStats1_OFFLINE already exists"}

[jackjlli]

Minor but LGTM