Zabbix

..F....... [ZBX-25820] fixed wrong calculations for items bits sending/receiving

* commit '00776c4cc1b2816a68ccd7160ea8bc3f2e2884db':
  ..F....... [ZBX-25820] fixed undefined index prev_time; do not set history for firstime call
  ..F....... [ZBX-25820] do not send previous value when test is run for first time
  ..F....... [ZBX-25820] simplified code which prepare previous value to be sent to server
  ..F....... [ZBX-25820] simplified code; removed check for empty prev_time, it is already validated
  ..F....... [ZBX-25820] fixed wrong calculations for items bits sent/received - PR fixes
  ..F....... [ZBX-25820] fixed wrong calculations for items bits sent/received - subissue
  ..F....... [ZBX-25820] fixed wrong calculations for items bits sending/receiving

(cherry picked from commit 0b5019b30641fbe0aed7ccd9be22d45ec2d29734)
(cherry picked from commit 5e52c3c115b5db467ace2bcaa1fd85d0da317e0b)