ui: PromQL Editor: experimental editor text input issues

[OGKevin]

Thanos, Prometheus and Golang version used:
Thanos: 0.21.1

What happened:
When using the UI provided by Thanos query frontend to query the data with experimental editor enabled, editing text inside the text query field does not work. Keystrokes are ignored and/or disappear immediately.

Screen.Recording.2021-06-24.at.16.26.38.mov

What you expected to happen:
When using the experimental editor, text input is handled correctly.

How to reproduce it (as minimally and precisely as possible):
Paste a block of text in the query field, try to edit the pasted text.

Full logs to relevant components:

Anything else we need to know:
This issue is present in Safari and Google Chrome

[OGKevin]

[OGKevin]

This might be related to #4184