Remove legacy repository cruft

This dates from the dark days when I dared to operate my own Jenkins instance. Never again.

Jenkinsfile

@@ -1,38 +0,0 @@
-pipeline {
-  agent none
-  options {
-    disableConcurrentBuilds()
-  }
-  stages {
-    stage('Build') {
-      agent {
-        docker {
-          image 'velocitypowered/openjdk8-plus-git:slim'
-          args '-v gradle-cache:/root/.gradle:rw'
-        }
-      }
-      steps {
-        sh './gradlew build --no-daemon'
-        archiveArtifacts 'proxy/build/libs/*-all.jar,api/build/libs/*-all.jar'
-      }
-    }
-    stage('Deploy') {
-      when {
-        expression {
-          GIT_BRANCH = sh(returnStdout: true, script: 'git rev-parse --abbrev-ref HEAD').trim()
-          return GIT_BRANCH == 'master'
-        }
-      }
-      agent {
-        docker {
-          image 'velocitypowered/openjdk8-plus-git:slim'
-          args '-v gradle-cache:/root/.gradle:rw -v maven-repo:/maven-repo:rw -v javadoc:/javadoc:rw'
-        }
-      }
-      steps {
-        sh 'export MAVEN_DEPLOYMENT=true; ./gradlew publish --no-daemon'
-        sh 'rsync -av --delete ./api/build/docs/javadoc/ /javadoc'
-      }
-    }
-  }
-}