fix(databricks): avoid creating UC volume in target schema

[nehaaprasaad]

fix : #722

summary

• Avoid creating Unity Catalog volumes in the user’s target schema during Databricks connection.

Changes

• Do not pass schema_name into ibis.databricks.connect().
• Use list_tables(database=...) in check_connection when schema_name is set.

Why

• Ibis memtable volumes follow the session default schema; BI schemas are often read-only.

[github-actions]

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[github-actions]

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