The sourcemap test in the e2e playground is now using async/await code.
This results in errors now with the Bazel TS compilation because it
detects that `expect` is returning a promise and should be awaited.

This happens due to the jasminewd2 types. We should just use the actual
jasmine types and not rely on the deprecated selenium control flow,
using explicit async/await in the whole test. This also solves the issue
with the source-map types being async/await now.

PR Close #46888