Legacy code in ubipop is removed [RHELDST-13337]

[jihupdc]

1. legacy code in ubipop is removed.
2. ubi-manifest is the only source of expected content for ubipop.

[codecov[bot]]

Codecov Report

Base: 97.24% // Head: 93.91% // Decreases project coverage by -3.33% :warning:

Coverage data is based on head (fd6bf70) compared to base (be974d5). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #196 +/- ## ========================================== - Coverage 97.24% 93.91% -3.34% ========================================== Files 7 7 Lines 1053 871 -182 ========================================== - Hits 1024 818 -206 - Misses 29 53 +24 ``` | [Impacted Files](https://codecov.io/gh/release-engineering/ubi-population-tool/pull/196?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=release-engineering) | Coverage Δ | | |---|---|---| | [ubipop/\_matcher.py](https://codecov.io/gh/release-engineering/ubi-population-tool/pull/196/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=release-engineering#diff-dWJpcG9wL19tYXRjaGVyLnB5) | `88.65% <ø> (-10.95%)` | :arrow_down: | | [ubipop/\_utils.py](https://codecov.io/gh/release-engineering/ubi-population-tool/pull/196/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=release-engineering#diff-dWJpcG9wL191dGlscy5weQ==) | `81.33% <ø> (-17.58%)` | :arrow_down: | | [ubipop/cli.py](https://codecov.io/gh/release-engineering/ubi-population-tool/pull/196/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=release-engineering#diff-dWJpcG9wL2NsaS5weQ==) | `95.91% <ø> (ø)` | | | [ubipop/\_\_init\_\_.py](https://codecov.io/gh/release-engineering/ubi-population-tool/pull/196/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=release-engineering#diff-dWJpcG9wL19faW5pdF9fLnB5) | `94.14% <100.00%> (-0.43%)` | :arrow_down: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=release-engineering). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=release-engineering)

:umbrella: View full report at Codecov.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.