Remove the Node Manager module from store

[loonggamma]

Context

• Up to 5 people were complaining that it's not working, on Discord.
• 1 bug created by user I can't install Massa Node #1202
  Problem with the main functionality (running a node) is verified by @peterjah

The need:
Remove the Node manager module in the Module store.

User flow
1. Users who didn't install the module:
a. user comes to Module store
b. he sees only Massa Wallet plugin

PR: massalabs/station-store#46

2. Users who installed the module:
Download count for last version: 979. We can assume that unique users are 1/3 of it.
a. user comes to Module store
b. user sees label 'beta' so that users can expect instability.
As we already have users with downloads, removing it for users
might give us some negative feedback. So a label should be sufficient.

Technical details
Give the technical insights so anyone in the team can tackle the tasks - Dev

QA testing
Does this task require some QA tests ?

• beta tag is displayed for installed node manager plugin
• followup action is taken to fix the quick win beta tag (see comment bellow)

[Thykof]

We will merge the PR to add the beta tag on the node manager plugin, but this PR is a quick win, we will keep this issue open or create a followup issue to do things properly: #1208 (comment)