chore: remove useless provider type

[ronething]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches
• Documentation
• Refactor
• Chore
• CI/CD or Tests

What this PR does / why we need it:

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[Copilot]

Pull Request Overview

This chore PR removes the unused API7EE provider type and updates related configurations and documentation.

• Removed API7EE constant and branch handling in internal/provider and internal/controller files
• Updated test framework namespace and documentation to align with the removal

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/e2e/scaffold/adc.go	Removed an obsolete comment
test/e2e/framework/framework.go	Updated namespace string from "api7-ee-e2e" to "apisix-e2e"
internal/provider/adc/adc.go	Removed the API7EE backend mode case
internal/controller/config/types.go	Removed the API7EE provider type constant
internal/controller/config/config.go	Changed default provider type from API7EE to Standalone and removed its validation case
docs/template/gv_list.tpl	Updated documentation text to remove references to API7
docs/crd/api.md	Updated documentation text to remove references to API7

Comments suppressed due to low confidence (3)

internal/provider/adc/adc.go:267

• The removal of the API7EE backend mode branch appears intentional. Please verify that all clients relying on the ADC behavior have been updated to use the supported backend modes to avoid integration issues.

		return nil

internal/controller/config/config.go:54

• Since the default provider type has changed from API7EE to Standalone, update the configuration documentation to clearly indicate this change, ensuring users are aware of the supported provider type.

			Type:          ProviderTypeStandalone,

test/e2e/framework/framework.go:35

• Ensure that the updated namespace 'apisix-e2e' is consistently used across all test configurations and environments to avoid any potential mismatch with existing test setups.

	_namespace = "apisix-e2e"