Remove unnecessary managed JDBC drivers from parent pom.xml

[lukaseder]

A few of our test dependencies are declared as managed JDBC drivers in the parent pom.xml <dependencyManagement> section. This is just for convenience of testing, but it isn't necessary. We have a shared jooq-test project that could declare these drivers, even as compile time dependencies to all tests, instead.

If the dependencies are declared in the parent pom.xml, then:

• We get CVE reports in our jOOQ Open Source Edition, even if it isn't affected (e.g. most recently: CVE-2022-46337)
• Users might get the same problem

Removing these drivers again would simplify the project structure with no negative impact on user code.

Affected drivers include:

• com.oracle.database.r2dbc:oracle-r2dbc
• io.r2dbc:r2dbc-h2
• io.r2dbc:r2dbc-mssql
• org.duckdb:duckdb_jdbc
• org.hsqldb:hsqldb
• org.mariadb:r2dbc-mariadb
• org.postgresql:postgresql
• org.postgresql:r2dbc-postgresql
• org.xerial:sqlite-jdbc

Drivers that continue being required include:

• com.h2database:h2
• com.microsoft.sqlserver:mssql-jdbc
• com.oracle.database.jdbc:ojdbc11