Oracle connector ignores user-credential-name/password-credential-name (per-session extraCredentials not honored)

[karthikchundi-commits]

Description

Every JDBC connector in Presto is expected to support per-session credential
passthrough via the standard user-credential-name / password-credential-name
config properties on BaseJdbcConfig, wired through automatically by
DriverConnectionFactory(Driver, BaseJdbcConfig) (see the constructor in
presto-base-jdbc/.../DriverConnectionFactory.java, and its usage of
JdbcIdentity.getExtraCredentials() in openConnection()).

The Oracle connector doesn't get this for free because
OracleClientModule.connectionFactory() needs to add Oracle-specific
connection properties (TLS truststore, oracle.jdbc.includeSynonyms), so it
builds its own DriverConnectionFactory directly instead of using the
BaseJdbcConfig-only constructor:

return new DriverConnectionFactory(
        new OracleDriver(),
        config.getConnectionUrl(),
        Optional.empty(),
        Optional.empty(),
        connectionProperties);

The two Optional.empty() arguments are userCredentialName and
passwordCredentialName - by hardcoding them to empty instead of reading
config.getUserCredentialName() / config.getPasswordCredentialName(), this
silently drops support for per-session extraCredentials for Oracle only.
Every other JDBC connector that relies on the default wiring (e.g. MySQL)
supports this correctly.

Impact

Any deployment using per-session Oracle credentials (extraCredentials set
per query/session rather than one static connection-user/connection-password
for the whole catalog) silently falls back to the static config credentials,
with no error - this can be a correctness/security surprise for multi-tenant
setups.

Proposed fix

Pass config.getUserCredentialName() / config.getPasswordCredentialName()
through instead of Optional.empty(), matching the pattern already used by
the DriverConnectionFactory(Driver, BaseJdbcConfig) convenience constructor.

Happy to submit a PR for this.