perf: skip gzip for SEA responses by default

[rahuls-db]

Description

Disables HTTP response compression by default for SQL Execution API requests by sending Accept-Encoding: identity. SEA inline results are already LZ4-compressed Arrow encoded in JSON, so the additional gzip layer adds server and client work.

The behavior is scoped to the SEA API client; OAuth, Thrift, CloudFetch, telemetry, and other HTTP traffic are unchanged. Bandwidth-constrained clients can restore the prior behavior with EnableSeaResponseCompression=1.

Testing

• mvn -pl jdbc-core test -Dtest=DatabricksConnectionContextTest,DatabricksSdkClientUserAgentTest — 164 passed, 0 failed.
• Spotless formatting ran successfully.
• The complete jdbc-core suite was attempted, but the pre-existing DatabricksArrowPatchTest.testConcurrentExecution stress test did not complete after several minutes and was stopped; no failures occurred before that test.

Telemetry Errors

• Not applicable — this PR does not add or change a telemetry-visible error.
• Applicable — the error uses DatabricksDriverErrorCode where appropriate, and any new code is uniquely numbered and tested.
• Applicable — its driver/server/user classification is linked, or maintainer help is requested because the author cannot access the classification.

Additional Notes to the Reviewer

This mirrors adbc-drivers/databricks#678 for the JDBC driver independent SEA implementation.

[peco-review-bot]

✅ No issues identified by the review bot.