[fix](bdbje) Reuse TLS config for group administration

[Yukang-Lian]

What problem does this PR solve?

Issue Number: N/A

Related PR: selectdb/selectdb-core#10972

Problem Summary: ReplicationGroupAdmin was created with the two-argument constructor, which builds its own default network channel factory instead of using the ReplicationConfig that initialized BDBJE. In a TLS-enabled replication group, administrative operations therefore attempt a plaintext connection. Pass the active RepNetConfig so group administration reuses the configured TLS channel factory.

Release note

BDBJE replication-group administration now uses the configured replication TLS transport.

Check List (For Author)

• Test: Unit Test: ./run-fe-ut.sh --run org.apache.doris.journal.bdbje.BDBEnvironmentTest#testReplicationGroupAdminReusesConfiguredNetworkFactory (1 passed)
• Behavior changed: Yes. ReplicationGroupAdmin reuses the active BDBJE network configuration.
• Does this need documentation: No

[hello-stephen]

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