Remove undo button

[nina-huangg]

This PR removes the undo button as the functionality is currently not implemented.

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
app.py	28	0	100%
blob.py	0	0	100%
init_mongo.py	122	11	91%	43–46, 78, 126–128, 170–177
routes
chat_routes.py	36	0	100%
file_routes.py	132	0	100%
moodboard_routes.py	135	2	99%	49, 143
search_routes.py	49	0	100%
tests
conftest.py	16	0	100%
test_app.py	12	0	100%
test_blob_storage.py	124	0	100%
test_chat_routes.py	103	0	100%
test_file_routes.py	289	0	100%
test_init_mongo.py	222	0	100%
test_moodboard_routes.py	264	0	100%
test_search_routes.py	110	0	100%
test_text_prompt.py	114	0	100%
usecases
text_prompt.py	77	0	100%
utils
blob_storage.py	54	0	100%
helpers.py	10	0	100%
TOTAL	1897	13	99%

Tests	Skipped	Failures	Errors	Time
105	0 💤	0 ❌	0 🔥	1.332s ⏱️

[chwawa]

Looks good! Thank you for making the change.