Overview

Add a server option --enableUnreleasedRolloutFlags that enables all IFR flags in the 'rollout' phase, and deprecate the existing --disableUnreleasedIFRFlags.

Background

Parent epic SPM-4898 makes 'rollout'-phase IFR flags default to off in the binary. Testing the "all rollout flags enabled" configuration then requires either knowing every flag name or a single switch. This option provides that switch, and is what we expect downstream teams and Atlas internal-trial/dogfooding environments to use.

Scope of Work

* Add --enableUnreleasedRolloutFlags (working name) enabling all flags in the 'rollout' phase.
* Also add --enableAllRolloutFlags (Appendix ask: enabling all IFR flags for internal-trial / Rollout-Bucket clusters).
* Deprecate --disableUnreleasedIFRFlags (incl. its resmoke plumbing, SERVER-104658): emit a deprecation warning, keep behavior until removal.
* Error if both --enableUnreleasedRolloutFlags and --disableUnreleasedIFRFlags are specified together.

Interaction with --setParameters

Document and test the precedence between these options and startup --setParameters that toggle individual IFR flags (e.g. --setParameters featureFlagX=true). Which wins when both are specified? Define the behavior, document it, and cover it with a test.

Acceptance Criteria

* New options exist and are documented in server options/help.
* Specifying both the enable and disable options fails with a clear error.
* Existing --disableUnreleasedIFRFlags users get a deprecation warning.
* Precedence vs --setParameters is defined, documented, and tested.
* Unit/integration coverage of the options' flag-state effect.