[Chore] Remove assertion feature

[wcchang1115]

PR checklist

• Ensure you have added or ran the appropriate tests for your PR.
• DCO signed

What type of PR is this?
chore

What this PR does / why we need it:

• piperider assertion is a deprecated feature, and we are going to remove it from the code base.

Which issue(s) this PR fixes:
sc-32471

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[codecov]

Codecov Report

Merging #917 (ce67823) into main (04e6a2e) will increase coverage by 0.50%.
The diff coverage is 62.50%.

@@            Coverage Diff             @@
##             main     #917      +/-   ##
==========================================
+ Coverage   47.99%   48.49%   +0.50%     
==========================================
  Files          78       63      -15     
  Lines       10756     9064    -1692     
==========================================
- Hits         5162     4396     -766     
+ Misses       5594     4668     -926     

Files	Coverage Δ
piperider_cli/cli.py	68.83% <ø> (+1.23%)	⬆️
piperider_cli/cli_utils/run_cmd.py	92.55% <ø> (ø)
piperider_cli/event/events.py	91.30% <ø> (-1.56%)	⬇️
piperider_cli/validator.py	23.52% <ø> (+1.30%)	⬆️
piperider_cli/runner.py	62.40% <62.50%> (+8.80%)	⬆️

... and 2 files with indirect coverage changes

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[kentwelcome]

LGTM