UTD on a thread summary when you change your display name

### Steps to reproduce

1. Write a message
2. Hold it > "Reply in thread" > send something
3. Go back > write `/myroomnick name`

### Outcome

#### What did you expect?

My name just changes in the room

#### What happened instead?

My name changes and the thread's summary text says "Unable to decrypt"

### Your phone model

_No response_

### Operating system version

_No response_

### Application version and app store

Tried latest `develop` and F-Droid

### Homeserver

_No response_

### Will you send logs?

No

### Will you submit a Pull Request?

No

Reproduce the thread-summary failure on the latest develop build using the listed steps, then trace the thread summary after changing the room display name with /myroomnick. Confirm the fix by verifying that the name changes without the summary becoming “Unable to decrypt.”

Written by the indexing model from the issue text.