Theme tests timesout often

[tanhakabir]

The theme tests timesout every time on the first build but on a re-run it's fine.

Seeing this:

1) test code generator
       theme import:
     Error: Timeout of 10000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (/Users/tanha/Documents/GitHub/msft-vscode-generator-code/test/test.js)
      at listOnTimeout (node:internal/timers:556:17)
      at processTimers (node:internal/timers:499:7)

[aeschli]

The tests fetch a theme file from http://www.monokai.nl/blog/wp-content/asdev/Monokai.tmTheme.
This seems to work for me, I don't see the time out. But we could change this to a local URL.

[aeschli]

Remove the test. We have another test that tests loading from a file.