citgm builds with small-icu

[richardlau]

Just noticed while editing the job config for #1959 that the CITGM job explicitly sets CONFIG_FLAGS to build small-icu:

We've recently made full-icu the default for master and the upcoming 13.x but the above will build Node.js in a non-default mode and probably means the CITGM run for nodejs/node#29522 didn't actually test what we thought it did ☹️.

I'll remove the explicit set after #1959 is resolved (don't want to change multiple things at once).

FYI @nodejs/releasers @nodejs/citgm

[richardlau]

We don't explicitly set any config flags in the job for Windows so we're okay there and its just (!) the UNIX/UNIX-like platforms.

[richardlau]

Made the change: https://ci.nodejs.org/view/Node.js-citgm/job/citgm-smoker/jobConfigHistory/showDiffFiles?timestamp1=2019-10-16_20-33-19&timestamp2=2019-10-16_20-35-51

Test run: https://ci.nodejs.org/view/Node.js-citgm/job/citgm-smoker/2060/