refactor(ivy): remove the tsc passthrough option (#32219)

This option makes ngc behave as tsc, and was originally implemented before
ngtsc existed. It was designed so we could build JIT-only versions of
Angular packages to begin testing Ivy early, and is not used at all in our
current setup.

PR Close #32219

packages/compiler/src/aot/compiler_options.ts

@@ -19,6 +19,6 @@ export interface AotCompilerOptions {
   fullTemplateTypeCheck?: boolean;
   allowEmptyCodegenFiles?: boolean;
   strictInjectionParameters?: boolean;
-  enableIvy?: boolean|'ngtsc'|'tsc';
+  enableIvy?: boolean|'ngtsc';
   createExternalSymbolFactoryReexports?: boolean;
 }