openui5 causes 35 MB of the 45 MB size for build.zip

(Just in case you don't know what the build.zip is: To avoid having everyone to build all frameworks, we're providing a build.zip that contains all dist folders (and some special tricks for special frameworks)) The size of the build.zip is mainly driven by the dist folders openui5 produces. A build without openui5 would result in ~10 MB and with openui we're at ~46 MB. openui5 is on the right hand side of the table so I'm not really willing to justify keeping 78% of the weight of build.zip for it.

@pskelin @aborjinik @albertlast Can you please improve the build file such the dist directory gets much smaller?