drop validation from CI, it does not work reliably enough

1 job for master in 2 minutes and 47 seconds (queued for 3 minutes and 39 seconds)
Status Job ID Name Coverage
  Build
failed #5993
fp-timing
build-iris.dev

00:02:47

 
Name Stage Failure
failed
build-iris.dev Build There is an unknown failure, please try again
make[1]: *** [all] Error 2
make[1]: Leaving directory '/builds/FP/iris-atomic'
Makefile:6: recipe for target 'all' failed
make: *** [all] Error 2

real 0m14.813s
user 0m27.537s
sys 0m1.877s
ERROR: Job failed: exit code 1