Attempting to view details of a key held by a worker results in a 404

**Describe the issue**:
When I'm running my scheduler, I navigate to the `info` tab, click on a worker and attempt to view information about one of the keys its holding.
Instead of viewing details about the key, I get a 404.

Note that the URL I'm being sent to is wrong; it has a spurious `+` in it.

http://localhost:8787/info/task/%28%27getitem-fused-assign-c649044b30796c30cb7b26ffb459d668%27%2C+0%29.html (what the worker's page sends me to)

fails, but

http://localhost:8787/info/task/%28%27getitem-fused-assign-c649044b30796c30cb7b26ffb459d668%27%2C0%29.html

is correct (I removed the `+` at the very end)

**Minimal Complete Verifiable Example**:

**Anything else we need to know?**:
Happy to contribute a PR but I'm having a bit of fun finding the relevant code

**Environment**:

- Dask & Distributed version: ` 2024.7.1`
- Python version: `3.10`
- Operating System: `Ubuntu`
- Install method (conda, pip, source): `pip`