ces: add proactive_execution_enabled to agent callbacks

[slevenick]

Added field coverage for proactiveExecutionEnabled on google_ces_agent callbacks (afterAgentCallbacks, afterModelCallbacks, afterToolCallbacks, beforeAgentCallbacks, beforeModelCallbacks, beforeToolCallbacks).

reference: b/550549027

ces: added `proactive_execution_enabled` field to callbacks in `google_ces_agent`

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit 5203721:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
google provider	View Diff	7 files changed, 518 insertions(+), 36 deletions(-)
google-beta provider	View Diff	7 files changed, 518 insertions(+), 36 deletions(-)
terraform-google-conversion	View Diff	1 file changed, 66 insertions(+)

Test report

Analytics

Total Tests	Passed	Skipped	Affected
79	78	0	1

Affected Service Packages

• ces

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Step 1: Replaying Mode

Action taken

Found 1 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit.

Click here to see the affected tests

• TestAccCESAgent_cesAgentBasicExample_update

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Step 2: Recording Mode

Recording Mode	Replaying Rerun	Test Name
✅ Log	✅	TestAccCESAgent_cesAgentBasicExample_update

🟢 All tests passed!

View the recording VCR build log or the debug logs folder for detailed results.

@slevenick, @melinath VCR tests complete for 5203721!

[slevenick]

@modular-magician reassign-reviewer

[github-actions]

Googlers: For automatic test runs see go/terraform-auto-test-runs.

@melinath, a repository maintainer, has been assigned to review your changes. If you have not received review feedback within 2 business days, please leave a comment on this PR asking them to take a look.

You can help make sure that review is quick by doing a self-review and by running impacted tests locally.