Remove validation warning for long voc ids on TPs >=6.0

Following up with NXS-3844 , the validation warning saying that "x characters have to be removed" on vocabulary ids longer than 12 characters is not necessary anymore.

TODO
Remove this validation warning for target platforms 6.0 and upper.
Keep it for target platforms <6.0 (because untested on these versions).

HOW TO TEST

• Set target platform to 9.1
• Create two vocabularies in Studio, named:
  helloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorld
  helloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorldhelloWorld2
• Make sure validation warning appears
• Deploy changes
• Check that validation warning disappears
• Change target platform to LTS 2015, 6.0, 5.8: validation warning should appear only on 5.8.