refactor(discord): replace Discord.Net bot login with a Discord webhook - #428

Version: 1.4.49.2965-discord-webhook

sarifId: 9d2626a8-cb9f-11f1-9caf-0692c18d575e

Published output sizes for linux-arm64: 114M /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot 24K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.CloudFormation.pdb 44K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.Discord.pdb 32K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.GitHub.pdb 16K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.Health.pdb 64K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.Json.pdb 16K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.ServiceModel.pdb 16K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.Watchtower.pdb 64K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.pdb 4.0K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/BuildBot.staticwebassets.endpoints.json 4.0K /build/runners/agents/build03/_work/BuildBot/BuildBot/server-dist/linux-arm64/appsettings.json