Extensions are being unintentionally marked as preview

[alvsan09]

This is issue was initially reported under the repository [1], issue [2],
However from the discussions, it is clear that Openvsx is treating the absence of the preview flag as true rather than false.

1. The logic shall be corrected
2. The data base should be updated to at least fix the entries having a revision containing the qualifier next.

[1] https://github.com/eclipse-theia/vscode-builtin-extensions
[2] eclipse-theia/vscode-builtin-extensions#105
[3] eclipse-theia/vscode-builtin-extensions#105 (comment)

[amvanbaren]

Hi @alvsan09, Thanks for reporting this issue. I've left a comment here: eclipse-theia/vscode-builtin-extensions#105 (comment)

[amvanbaren]

I'm closing this issue in favor of eclipse-theia/vscode-builtin-extensions#105