ci: tests: do not build all tests when docs/images change
ci: tests: do not build all tests when docs/images change

When we change documentation or board images, do not build all tests for
this board. Only add more tests when actual code has changed.

Signed-off-by: Anas Nashif <0d9952ec84ac43c159f6b7e7ed99a9080c00dd6e@intel.com>

GiulianoFranchetto/zephyr,finikorg/zephyr,ldts/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,finikorg/zephyr,nashif/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,explora26/zephyr,Vudentz/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,explora26/zephyr,explora26/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,nashif/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,ldts/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr