Caused by {rB85421c4fab02}.
Above commit treated `SOCK_RGBA` and `SOCK_STRING` the same in
`std_node_socket_draw`.
That would turn a RGBA button into a text button (for attribute search),
leading to trouble.
Note these were just treated the same prior to above commit because both
were doing the layout split.
Now just give RGBA sockets their own case.
Maniphest Tasks: T86373
Differential Revision: https://developer.blender.org/D10646
9ba1ff1c63