[fix](paimon) reconnect stale jdbc catalog

[xylaaaaa]

Problem

• paimon 1.1.1 JDBC catalog keeps long-lived JDBC connections in JdbcClientPool
• borrowed connections are reused without validity checks
• after MySQL wait_timeout, read paths can fail with stale connection errors such as CJCommunicationsException / Broken pipe

Fix

• detect stale JDBC connection failures in PaimonExternalCatalog for JDBC catalogs
• reset the catalog to uninitialized, rebuild the underlying Paimon catalog, and retry read operations once
• keep retry scope on read paths only to avoid replaying mutating DDL operations
• clear metadataOps and catalog references during close to prevent stale objects from being reused

Tests

• added PaimonJdbcCatalogReconnectTest
• verified the targeted FE UT passed: Tests run: 3, Failures: 0, Errors: 0, Skipped: 0

[hello-stephen]

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