FF fix Delete Modal: wait on http response before close

[danoswaltCL]

Modals should stay open after primary button click. All of our modals should follow this same UX pattern if there's an http call that is fired on primary click:

• Disable the primary button so that the user doesn't double-click
• Close on success response received.
• OR if error, stay open and re-enable the button.

[ppratikcr7]

@Yagnik56 @zackcl The delete modal seems to be bit off in size as compared to other modals.

[zackcl]

The width of the "Delete Feature Flag" modal is 480px in the original design in Figma. I think that should be correct in size.