Fixed "clip histogram" button not resetting in some cases

[hotzenklotz]

This PR fix a small issue with an AsyncButton for clipping the histogram not resetting to it's "base"/cklickable state in some case but instead "loading"/"spinning" forever.

URL of deployed dev instance (used for testing):

• https://___.webknossos.xyz

Steps to test:

• Move to an area with no data ("black")
• Click "clip histogram" button
• Oberserve that the button turns into a spinner and returns to its base state ready for clicking again

Issues:

• fixes After histogram clipping fails (e.g. no data in viewport), button stays disabled #6341

---

(Please delete unneeded items, merge only when none are left open)

• Updated (unreleased) changelog
• Updated (unreleased) migration guide if applicable
• Updated documentation if applicable
• Adapted wk-connect if datastore API changes
• Adapted wk-libs python client if relevant API parts change
• Needs datastore update after deployment
• Ready for review

[philippotto]

awesome, thank you for debugging this 👍