test: cover resource id initializers

[neu-hsc]

What this PR does

This PR adds focused unit coverage for the rm-datasource resource id initializer path:

• verifies ResourceIdInitializerRegistry selects DB-specific initializers and falls back to the default initializer
• covers query-string stripping for default and MySQL resource ids
• covers MySQL load-balance host normalization
• covers PostgreSQL currentSchema preservation and separator normalization
• covers DM schema filtering, Oracle/Oscar username suffixing, and SQL Server identity property filtering

Why

This helps increase rm-datasource module test coverage for #1714 without changing runtime behavior.

Tests

Ran the focused Maven reactor test locally:

mvn -pl rm-datasource -am -Dtest=ResourceIdInitializerTest -DfailIfNoTests=false -DfailIfNoSpecifiedTests=false test

Local note: I used a temporary Maven settings file only to redirect the local repository away from my read-only Maven installation directory.