[Fix a Bug] add supported for Oracle CDB mode at OracleIncrementalSource

[luckes-yang]

it could not read the PDB tables when using OracleIncrementalSource at Oracle CDB mode,Therefore, check whether the pdb is empty when creating a connection. If it is not empty, switch to the pdb session

[yuxiqian]

Thanks for your contribution! Before this PR could be merged, could you please rebase it with latest master branch?

[github-actions[bot]]

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