Preserve environment when editing Network Policies

What does this MR do?

Prior to this change edit page is loaded with the default environment therefore failing on updating and deletion. The workaround is the user manually changing the environment through the environment picker to match the network policy being edited.

This change preserves the environment when editing network policies. Editing page will provide environment id from the controller which will set the current environment id to the current state while reflecting on the environment picker.

Related to: #223670 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team