[BUG] Fix issues introduced human readable task_runtime change

[martin-mat]

Because of not considering review comments at this PR
#2007
and merging it as an different PR
#2009
following issues were introduced:

• excess "seconds" word in the log output

INFO -- cnf-testsuite: upsert_task: task: privileged has status: passed and is awarded: 5 points. Runtime: 0 hours, 0 minutes, and 1 seconds      seconds↲

• leaving commented code in points.cr
  https://github.com/cnti-testcatalog/testsuite/blob/main/src/tasks/utils/points.cr#L439

# task_runtime = (end_time - start_time).milliseconds
task_runtime = (end_time - start_time)

• difficult-to-parse task_runtime format it results yaml (and not consistent with format of start_time and end_time):

- name: privileged↲
  status: passed↲
  type: ""↲
  points: 5↲
  start_time: 2024-04-29 17:13:36.293093773↲
  end_time: 2024-04-29 17:13:37.333084104↲
  task_runtime: 0 hours, 0 minutes, and 1 sec