refactor(@schematics/angular): remove migration of non LTS versions

With this change we remove migrations for non LTS version of Angular CLI.

Author: alan-agius4

packages/schematics/angular/migrations/migration-collection.json

@@ -1,53 +1,13 @@
 {
   "schematics": {
-    "migration-01": {
-      "version": "6.0.0-beta.8",
-      "factory": "./update-6",
-      "description": "Update an Angular CLI project to version 6."
-    },
-    "migration-02": {
-      "version": "7.0.0-beta.0",
-      "factory": "./update-7",
-      "description": "Update an Angular CLI project to version 7."
-    },
-    "migration-03": {
-      "version": "7.0.0-rc.0",
-      "factory": "./update-7/index#polyfillMetadataRule",
-      "description": "Update an Angular CLI project to version 7."
-    },
-    "migration-04": {
-      "version": "7.1.0-beta.0",
-      "factory": "./update-7/index#typeScriptHelpersRule",
-      "description": "Update an Angular CLI project to version 7."
-    },
-    "migration-05": {
-      "version": "7.0.4",
-      "factory": "./update-7",
-      "description": "Update an Angular CLI project to version 7."
-    },
-    "migration-06": {
-      "version": "7.0.3",
-      "factory": "./update-7/index#updateDevkitBuildNgPackagr",
-      "description": "Update an Angular CLI project to version 7."
-    },
-    "migration-07": {
-      "version": "8.0.0-beta.12",
-      "factory": "./update-8",
-      "description": "Update an Angular CLI project to version 8."
-    },
-    "migration-08": {
-      "version": "8.0.0-beta.14",
-      "factory": "./update-8/#updateLazyModulePaths",
-      "description": "Update an Angular CLI project to version 8."
-    },
     "workspace-version-9": {
       "version": "9.0.0-beta.0",
       "factory": "./update-9",
       "description": "Angular Workspace migration. Update an Angular CLI workspace to version 9."
     },
     "lazy-loading-syntax": {
       "version": "9.0.0-next.6",
-      "factory": "./update-8/#updateLazyModulePaths",
+      "factory": "./update-12/update-lazy-module-paths",
       "description": "Lazy loading syntax migration. Update lazy loading syntax to use dynamic imports."
     },
     "schematic-options-9": {
@@ -142,7 +102,7 @@
     },
     "lazy-loading-string-syntax": {
       "version": "12.0.0-next.4",
-      "factory": "./update-8/#updateLazyModulePaths",
+      "factory": "./update-12/update-lazy-module-paths",
       "description": "Lazy loading syntax migration. Update lazy loading string syntax to use dynamic imports."
     },
     "remove-deprecated-i18n-options": {

packages/schematics/angular/migrations/update-8/update-lazy-module-paths.ts renamed to packages/schematics/angular/migrations/update-12/update-lazy-module-paths.ts

@@ -37,7 +37,7 @@ function* visit(directory: DirEntry): IterableIterator<ts.SourceFile> {
   }
 }
 
-export function updateLazyModulePaths(): Rule {
+export default function(): Rule {
   return tree => {
     for (const sourceFile of visit(tree.root)) {
       let recorder: UpdateRecorder | undefined;

packages/schematics/angular/migrations/update-8/update-lazy-module-paths_spec.ts renamed to packages/schematics/angular/migrations/update-12/update-lazy-module-paths_spec.ts

@@ -50,7 +50,7 @@ describe('Migration to version 8', () => {
     it('should replace the module path string', async () => {
       tree.create(lazyRoutePath, Buffer.from(lazyRoute));
 
-      await schematicRunner.runSchematicAsync('migration-08', {}, tree).toPromise();
+      await schematicRunner.runSchematicAsync('lazy-loading-string-syntax', {}, tree).toPromise();
       await schematicRunner.engine.executePostTasks().toPromise();
 
       const routes = tree.readContent(lazyRoutePath);
@@ -63,7 +63,7 @@ describe('Migration to version 8', () => {
     it('should replace the module path string in a child path', async () => {
       tree.create(lazyRoutePath, Buffer.from(lazyChildRoute));
 
-      await schematicRunner.runSchematicAsync('migration-08', {}, tree).toPromise();
+      await schematicRunner.runSchematicAsync('lazy-loading-string-syntax', {}, tree).toPromise();
       await schematicRunner.engine.executePostTasks().toPromise();
 
       const routes = tree.readContent(lazyRoutePath);
@@ -77,7 +77,7 @@ describe('Migration to version 8', () => {
     it('should replace the module path string when file has BOM', async () => {
       tree.create(lazyRoutePath, '\uFEFF' + Buffer.from(lazyRoute).toString());
 
-      await schematicRunner.runSchematicAsync('migration-08', {}, tree).toPromise();
+      await schematicRunner.runSchematicAsync('lazy-loading-string-syntax', {}, tree).toPromise();
       await schematicRunner.engine.executePostTasks().toPromise();
 
       const routes = tree.readContent(lazyRoutePath);