Tidy up 11-11-{7,8,9} 7-inch tablet layouts

* Add gutters between shift keys and letters for nordic
* Slightly narrower 3rd-row letter keys for bulgarian
* Remove "ъ" key from 1st-row of east_slavic
* Remove right shift for 11-11-9 east_slavic and south_slavic

Bug: 6422448
Change-Id: I2311bd475aabda51080f0be3714fabffa65b2009