[Oracle Module] Refactor module to properly use host parsers instead of doing its own parsing of hosts

[yug-rajani]

Problem

Oracle Metricbeat Module currently does its own parsing of hosts instead of using host parsers. Metricsets should rely on the host available in HostData.
For example,
If we look to the postgresql module, the url parser receives a single url to parse, and returns a single HostData, that contains a single host and is used like this by the metricset (here), without having to check the raw host configuration.

Solution

Metricbeat should instantiate one metricset per host, and the metricset shouldn't need to do any special handling to support multiple hosts. This module needs to be refactored to properly use host parsers instead of doing its own parsing of hosts. Using HostData is the only way a metricset instance has to know what host to use when multiple hosts are configured.

Use cases

• When parsing the configured host, it allows to set in the HostData the Host, that is later used for service.address.
• It abstracts the handling of multiple hosts, each metricset instance receives a single HostData with the host they have to use.

Related Converations

• [Oracle Module] Handle special characters for Oracle connection string properly #31368 (comment)
• [Oracle Module] Handle special characters for Oracle connection string properly #31368 (comment)