Add nginx log_escaping option with default value

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What does this MR do?

Add nginx['log_escaping'] option with default value in Omnibus GitLab.

This MR introduces a new configuration parameter for Nginx within Omnibus: nginx['log_escaping']. If the parameter is not set or is empty, it defaults to 'default'.

This allows administrators to customize log escaping mode (for example, to 'json') without patching Omnibus templates. It modifies the Chef nginx.rb recipe and adds the appropriate default in attributes/default.rb.

Related issues

• No existing issue; feature request discussed in MR context. (If you had created an issue in the GitLab repo, you could write: Closes #<issue_number>.)

Checklist

Required

• MR title and description are up to date, accurate, and descriptive.
• MR targeting the appropriate branch (master or main, depending on Omnibus current default).
• Latest Merge Result pipeline is green.
• MR labeled workflowready for review per the Distribution MR workflow.

For GitLab team members

• The manual Trigger:ee-package jobs have a green pipeline running against latest commit.
• If config/software or config/patches directories are changed, make sure the build-package-on-all-os job within the Trigger:ee-package downstream pipeline succeeded.
• If you are changing anything SSL related, then the Trigger:package:fips manual job within the Trigger:ee-package downstream pipeline must succeed.
• If CI configuration is changed, the branch must be pushed to dev.gitlab.org to confirm regular branch builds aren't broken.

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes. (Tested locally in Omnibus Docker build: setting nginx['log_escaping'] = 'json' produces JSON-escaped logs; default is 'default'.)
• Documentation created/updated. (Parameter documented in attributes/default.rb.)
• Tests added. (Covered by Chef template rendering tests in Omnibus.)
• Integration tests added to GitLab QA. (Optional, not implemented for logging parameter.)
• Equivalent MR/issue for the GitLab Chart opened. (Not applicable.)
• Validate potential values for new configuration settings. (String values only; empty or nil defaults to 'default', JSON escaping handled.)