Fix insiders definition (#18832)

* Add odd number definition for insiders versions

* Add comment

Author: luabud

src/client/common/application/applicationEnvironment.ts

@@ -88,7 +88,8 @@ export class ApplicationEnvironment implements IApplicationEnvironment {
     }
     public get extensionChannel(): Channel {
         const version = parse(this.packageJson.version);
-        return !version || version.prerelease.length > 0 ? 'insiders' : 'stable';
+        // Insiders versions are those that end with '-dev' or whose minor versions are odd (even is for stable)
+        return !version || version.prerelease.length > 0 || version.minor % 2 == 1 ? 'insiders' : 'stable';
     }
     public get uriScheme(): string {
         return vscode.env.uriScheme;