Revert "feat: joining more chats for more data"

This reverts commit 7216e11.

This was better in theory than practice. The joining of channels got so
backed up that it took 17 minutes to finish the first loop of joins.
Meaning anyone that goes live between 0-17 minutes of the application
starting up will not be joined until the 17 minutes is over.

Author: ProgrammingByPermutation

src/Nullinside.Api.TwitchBot/Services/MainService.cs

@@ -180,22 +180,13 @@ protected override Task ExecuteAsync(CancellationToken stoppingToken) {
               // Join all the channels we're a mod in. Why do we limit it to channels we are a mod in? Twitch changed
               // its chat limits so that "verified bots" like us don't get special treatment anymore. The only thing
               // that skips the chat limits is if it's a channel you're a mod in.
-              var bannedUsers = (await GetBannedUsers(db, stoppingToken))
-                .Where(u => !string.IsNullOrWhiteSpace(u.TwitchId))
-                .Select(u => u.TwitchId!.Trim())
-                .ToHashSet();
-              var allModdedAndNotBannedUsers = moddedChannels
-                .Where(m => !bannedUsers.Contains(m.broadcaster_id));
-              var joinChannels = usersWithBotEnabled
-                .Select(u => u.TwitchUsername)
-                .Concat(allModdedAndNotBannedUsers.Select(j => j.broadcaster_login));
-              foreach (var channel in joinChannels) {
-                if (string.IsNullOrWhiteSpace(channel)) {
+              foreach (User channel in usersWithBotEnabled) {
+                if (string.IsNullOrWhiteSpace(channel.TwitchUsername)) {
                   continue;
                 }
 
-                await _client.AddMessageCallback(channel, OnTwitchMessageReceived);
-                await _client.AddBannedCallback(channel, OnTwitchBanReceived);
+                await _client.AddMessageCallback(channel.TwitchUsername, OnTwitchMessageReceived);
+                await _client.AddBannedCallback(channel.TwitchUsername, OnTwitchBanReceived);
               }
             }
 
@@ -299,7 +290,7 @@ orderby user.TwitchLastScanned
   /// <param name="db">The database.</param>
   /// <param name="stoppingToken">The stopping token.</param>
   /// <returns>The list of users with the bot enabled.</returns>
-  private async Task<List<User>> GetBannedUsers(INullinsideContext db, CancellationToken stoppingToken) {
+  private async Task<List<User>?> GetBannedUsers(INullinsideContext db, CancellationToken stoppingToken) {
     return await
       (from user in db.Users
         orderby user.TwitchLastScanned