[Flow Control]: Cleanup: Remove PriorityName from PriorityBandConfig

[LukeAVanDrie]

What would you like to be added:
I would like to remove the PriorityName string field from the PriorityBandConfig struct and all downstream usages (metrics, logs, accessors).

Proposed Changes:

1. Remove PriorityName from pkg/epp/flowcontrol/registry/config.go (and elsewhere in pkg/epp/flowcontrol).
2. Remove validation logic checking for duplicate names.
3. Update the DefaultPriorityBand template logic to stop generating names like Dynamic-<int>.
4. Update Stats() and Prometheus metrics to identify bands solely by their integer Priority value.

Why is this needed:
Currently, priority bands are assigned a human-readable name (e.g., "High", "Dynamic-100"). However, the relationship between InferenceObjective resources and Priority Bands is N:1; multiple objectives can map to the same integer priority level.

Trying to assign a single name to a band shared by multiple objectives (e.g., "TenantA,TenantB") is complex and leads to ambiguous or confusing observability data.

Since the integer Priority is the unique identifier for the band, the string name provides little mechanical value and invites confusion. Removing it simplifies the configuration model and eliminates the ambiguity.

See: #2006 (comment).

In logging, we should replace this with the InferenceObjective info (Model) bound to the request. This info is being passed through in #2010.

[LukeAVanDrie]

/help
/good-first-issue

[k8s-ci-robot]

@LukeAVanDrie:
This request has been marked as suitable for new contributors.

Guidelines

Please ensure that the issue body includes answers to the following questions:

• Why are we solving this issue?
• To address this issue, are there any code changes? If there are code changes, what needs to be done in the code and what places can the assignee treat as reference points?
• How can the assignee reach out to you for help?

For more details on the requirements of such an issue, please see here and ensure that they are met.

If this request no longer meets these requirements, the label can be removed
by commenting with the /remove-good-first-issue command.

Details

In response to this:

/help
/good-first-issue

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[rahulgurnani]

/milestone Flow Control

[AryanBagade]

@rahulgurnani if its open for external contributors, would love to work on it!

[LukeAVanDrie]

Yes, this is open, thank you!

All instances are under pkg/epp/flowcontrol/.... Removing the field/methods from these four type definitions should flag every instance.

1. gateway-api-inference-extension/pkg/epp/flowcontrol/contracts/registry.go

   Line 214 in 36ca5ab

   PriorityName string

2. gateway-api-inference-extension/pkg/epp/flowcontrol/framework/mocks/mocks.go

   Line 76 in 36ca5ab

   func (m *MockPriorityBandAccessor) PriorityName() string { return m.PriorityNameV }

3. gateway-api-inference-extension/pkg/epp/flowcontrol/framework/policies.go

   Line 174 in 36ca5ab

   PriorityName() string

4. gateway-api-inference-extension/pkg/epp/flowcontrol/registry/config.go

   Line 152 in 36ca5ab

   PriorityName string

Currently, we are not propagating the InferenceObjective info to the Flow Control layer. I am adding this in #2010 for metrics labels. At the moment, I would just prioritize removing instances rather than replacing them. We can do that as a followup depending on which PR gets merged first.

Please let me know if you have any questions!

[AryanBagade]

@LukeAVanDrie thanks for the info, will create a PR soon!