Booloader Update button expected time should be shorter

If users trigger a bootloader update through MP, a window pops up saying that the procedure could take a few minutes but in practice it is almost instantaneous. I think we should change the message, perhaps just remove the expected time portion completely.

AP wiki: https://ardupilot.org/copter/docs/common-bootloader-update.html

Reproduce a bootloader update through Mission Planner and search the UI resources or source for the popup text. Done means the message no longer claims the procedure takes a few minutes; verify the updated wording in the bootloader update flow and consult the linked AP wiki for context.

Written by the indexing model from the issue text.