Remove trivial tray features

[wusyong]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

[wusyong]

@FabianLars @lucasfernog Do you agree on this? If so, I want to publish this as soon as possible.

[FabianLars]

Fine by me 👍

What do you think about removing the tray feature from the default features?

[wusyong]

Sure, I think it's also more reasonable.

[lucasfernog]

Seems good, we can deal with it at Tauri.

[nazar-pc]

I traced ayatana removal to here, why did it happen?
I can't build it on Ubuntu 22.04 anymore because I have libayatana-appindicator instead of libappindicator installed.

Before this PR ayatana-tray was the default feature, now it is not possible to use at all, I'm confused why this PR is a "feature" and not a major breaking change.