`ls_rollup_bundle` is no longer needed since we could invoke `ng_rollup_bundle`
directly.
Background: language service runs rollup to produce a single file to reduce
startup time in the editor. However, due to the need to load dynamic versions
of typescript at runtime (think the case where users can change typescript
version in their editor), we hack the "banner" to export a CommonJS default function,
so that we could dynamically load the typescript module provided at runtime via AMD
and use it throughout the implementation.
PR Close#38086
bd71f10234