[all sinks] Improve the different elements naming when notified/default service path is /

[frbattid]

Current behaviour:

• OrionHDFSSink: /user/myuser/myservice//myentityId_myentityType/myentityId_myentityType.txt
• OrionMySQLSink: database myservice, table _myentityId_myentityType
• OrionCKANSink: orgName myservice, pkgName myservice, resName myentityId_myentityType
• OrionSTHSink/OrionMongoSink: database sth_myservice, collection sth_/_myentityId_myentityType
• OrionKafkaSink: error --> "Path must not end with / character" !!!
• OrionDynamoDBSink: myservice__myentityId_myentityType
• OrionPostgreSQLSink: schema myservice, table _myentityId_myentityType

In addition, subsvc field in log4j logs is empty when / is notified (or configured as default).

Do we accept this default behaviour? Alternatives?

My proposal:

• OrionHDFSSink --> / instead of //
• OrionMySQLSink --> remove the initial _
• OrionCKANSink --> it's OK
• OrionMongoSink/OrionSTHSink --> they are OK
• OrionKafkaSink --> must be fixed
• OrionDynamoDBSink --> _ instead of __
• OrionPostgreSQLSink --> remove the initial _

[frbattid]

This must be applied both to release/0.13.0 and release/0.14.0

[manucarrace]

LGTM

[frbattid]

Implemented in PR #883 and PR #896 (develop branch)
Implemented in PR #886 and PR #897 (release/0.13.0 branch)