Revise boolean preservation test to trigger Update via request_max_bytes

[philippschulte]

Change summary

This PR updates the acceptance test for preserving optional boolean fields in the logging_kafka block to ensure it actually exercises the Update() path.

Previously, the test modified only the name field — which causes a resource recreation due to ForceNew behavior. As a result, the test didn't confirm that use_tls and parse_log_keyvals were preserved during an update, defeating the purpose of the fix introduced in #1147.

To correct this:

• The new test modifies a safe, non-ForceNew field: request_max_bytes
• name remains constant to ensure an in-place update
• Boolean fields are explicitly verified before and after the update

Outcome:

• Ensures Update() is invoked
• Validates use_tls and parse_log_keyvals are preserved as expected

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