feat!: Remove old scale down mechanism (< 0.19.0) (#2519)

Migration:
Option 1, upgrade to 2.x could cause orphan instances which will not be terminated by the scale-down function, thoses instances needs to be removed manual.
Option 2, upgrade first to a verions 1.x and keep this version running till all instances before the upgrade are terminated. Next upgrade to 2.x.

Author: npalm

modules/runners/lambdas/runners/src/scale-runners/scale-down.test.ts

@@ -444,7 +444,7 @@ describe('scaleDown', () => {
 
       expect(mockOctokit.apps.getRepoInstallation).toBeCalledTimes(2);
       expect(mockOctokit.apps.getOrgInstallation).toBeCalledTimes(1);
-      expect(terminateRunner).toBeCalledTimes(8);
+      expect(terminateRunner).toBeCalledTimes(7);
       for (const toTerminate of RUNNERS_ALL_REMOVED) {
         expect(terminateRunner).toHaveBeenCalledWith(toTerminate.instanceId);
       }
@@ -558,7 +558,7 @@ describe('scaleDown', () => {
 
       expect(mockOctokit.apps.getRepoInstallation).toBeCalledTimes(2);
       expect(mockOctokit.apps.getOrgInstallation).toBeCalledTimes(1);
-      expect(terminateRunner).toBeCalledTimes(8);
+      expect(terminateRunner).toBeCalledTimes(7);
       for (const toTerminate of RUNNERS_ALL_REMOVED) {
         expect(terminateRunner).toHaveBeenCalledWith(toTerminate.instanceId);
       }

modules/runners/lambdas/runners/src/scale-runners/scale-down.ts

@@ -220,21 +220,6 @@ async function listAndSortRunners(environment: string) {
   });
 }
 
-/**
- * We are moving to a new strategy to find and remove runners, this function will ensure
- * during migration runners tagged in the old way are removed.
- */
-function filterLegacyRunners(ec2runners: RunnerList[]): RunnerInfo[] {
-  return ec2runners
-    .filter((ec2Runner) => ec2Runner.repo || ec2Runner.org)
-    .map((ec2Runner) => ({
-      instanceId: ec2Runner.instanceId,
-      launchTime: ec2Runner.launchTime,
-      type: ec2Runner.org ? 'Org' : 'Repo',
-      owner: ec2Runner.org ? (ec2Runner.org as string) : (ec2Runner.repo as string),
-    }));
-}
-
 function filterRunners(ec2runners: RunnerList[]): RunnerInfo[] {
   return ec2runners.filter((ec2Runner) => ec2Runner.type) as RunnerInfo[];
 }
@@ -256,12 +241,9 @@ export async function scaleDown(): Promise<void> {
     logger.debug(`No active runners found for environment: '${environment}'`, LogFields.print());
     return;
   }
-  const legacyRunners = filterLegacyRunners(ec2Runners);
-  logger.debug(JSON.stringify(legacyRunners), LogFields.print());
-  const runners = filterRunners(ec2Runners);
 
+  const runners = filterRunners(ec2Runners);
   await evaluateAndRemoveRunners(runners, scaleDownConfigs);
-  await evaluateAndRemoveRunners(legacyRunners, scaleDownConfigs);
 
   const activeEc2RunnersCountAfter = (await listAndSortRunners(environment)).length;
   logger.info(