fix(ftconf): also mark secret_access_key key as sensitive

[keynslug]

Fixes EMQX-11026.

Summary

🤖 Generated by Copilot at 81cf619

Improve masking of sensitive keys in logs and configs. Add secret_access_key to the list of sensitive keys and handle different key types in emqx_utils:mask_config/1.

PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• Added tests for the changes
• Added property-based tests for code which performs user input validation
• Changed lines covered in coverage report
• Change log has been added to changes/(ce|ee)/(feat|perf|fix)-<PR-id>.en.md files
• For internal contributor: there is a jira ticket to track this change
• Created PR to emqx-docs if documentation update is required, or link to a follow-up jira ticket
• Schema changes are backward compatible

[coveralls]

Pull Request Test Coverage Report for Build 6299000571

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• 25 unchanged lines in 14 files lost coverage.
• Overall coverage increased (+0.003%) to 82.752%

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Files with Coverage Reduction	New Missed Lines	%
apps/emqx_connector/src/emqx_connector_jwt_worker.erl	1	89.47%
apps/emqx_ft/src/emqx_ft.erl	1	86.72%
apps/emqx_ft/src/emqx_ft_storage_exporter.erl	1	88.24%
apps/emqx_ft/src/emqx_ft_storage_fs.erl	1	82.84%
apps/emqx_resource/src/emqx_resource_buffer_worker.erl	1	93.26%
apps/emqx/src/emqx_cm.erl	1	90.32%
apps/emqx/src/emqx_connection.erl	1	83.15%
apps/emqx/src/emqx_limiter/src/emqx_limiter_schema.erl	1	85.71%
apps/emqx/src/emqx_os_mon.erl	1	91.78%
apps/emqx/src/emqx_router_helper.erl	1	88.68%

Totals
Change from base Build 6298036007:	0.003%
Covered Lines:	33614
Relevant Lines:	40620

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💛 - Coveralls