LastGenre plugin not respecting "noautotag" flag on "beet import"

Hey—

I've asked this question on IRC and since found the reason, which I believe is a bug or at least unexpected behaviour: I've imported my old library as-is with "--noautotag".

Today I ran "beet update" on my library and I saw that it rewrites some genres based on the tags in the files (Which is expected). What's unexpected is that it updates them from a genre to the one in the file itself. I was not sure where this existing genre came from if "noautotag" was enabled.


Today I realized that this is happening because of the [LastGenre](https://beets.readthedocs.io/en/stable/plugins/lastgenre.html) plugin which has this enabled as a default option. The genres match the first result on Last.fm (Including the typical Last.fm inaccuracies "hip-hop" and "hip hop" etc.), so it's definitely coming from this plugin.

```
auto: Fetch genres automatically during import. Default: yes.
```

I feel like the LastGenre plugin should respect the `noautotag` flag based on the documentation of the "noautotag" flag.

### Setup

```
beets version 2.2.0
Python version 3.8.15
plugins: bandcamp, discogs, edit, fetchart, fromfilename, lastgenre, lastimport, plexupdate
```