fix(sql): return errors for invalid pool properties

[mattfaltyn]

Which issue does this PR close?

• Closes SQL catalog panics on invalid pool property values #2846.

What changes are included in this PR?

• Parse SQL catalog connection-pool properties without panicking.
• Return ErrorKind::DataInvalid with the invalid property, value, and parse error.
• Add regression coverage for pool.max-connections, pool.idle-timeout, and pool.test-before-acquire.

Are these changes tested?

• cargo test -p iceberg-catalog-sql --all-features --lib
• cargo fmt --all -- --check
• cargo clippy -p iceberg-catalog-sql --all-targets --all-features -- -D warnings
• Re-ran the issue reproducer and confirmed the malformed value returns a structured error while a valid value still initializes the catalog.