[RHELC-1753] Handle yum failing on trying to reach inaccessible --enablerepo repos

[hosekadam]

Avoid reaching unaccessible repositories provided by user using --enablerepo argument. Those repos are manually disabled during analysis, but when user provides unreachable repo the analysis would fail.

This change adds check if provided repos are accessible - if not, those unaccessible ones are removed from the list for manual disable during analysis.

Jira Issues:

• RHELC-1753

Checklist

• [x] PR has been tested manually in a VM (either author or reviewer)
• [x] Jira issue has been made public if possible
• [x] [RHELC-] or [HMS-] is part of the PR title
• [x] Label depicting the kind of PR it is
• [x] PR title explains the change from the user's point of view
• [x] Code and tests are documented properly
• [ ] The commits are squashed to as few commits as possible (without losing data)
• [ ] When merged: Jira issue has been updated to Release Pending if relevant

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.12%. Comparing base (7c3db22) to head (3ba3fe6). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1425 +/- ## ========================================== + Coverage 96.09% 96.12% +0.03% ========================================== Files 72 72 Lines 5146 5186 +40 Branches 889 896 +7 ========================================== + Hits 4945 4985 +40 Misses 119 119 Partials 82 82 ``` | [Flag](https://app.codecov.io/gh/oamg/convert2rhel/pull/1425/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | Coverage Δ | | |---|---|---| | [centos-linux-7](https://app.codecov.io/gh/oamg/convert2rhel/pull/1425/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | `91.65% <100.00%> (+0.06%)` | :arrow_up: | | [centos-linux-8](https://app.codecov.io/gh/oamg/convert2rhel/pull/1425/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | `92.50% <100.00%> (+0.05%)` | :arrow_up: | | [centos-linux-9](https://app.codecov.io/gh/oamg/convert2rhel/pull/1425/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | `92.62% <100.00%> (+0.05%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg#carryforward-flags-in-the-pull-request-comment) to find out more.

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[hosekadam]

Note for reviewers: I used the singleton pattern as we don't exactly know the order of actions and possible where the repo.py would be imported. If we decide to create an instance inside the repo.py we can end up preparing the disablerepo list when we don't actually need it (and possibly the analysis can fail in earlier actions).

This solution creates an instance when it's needed and also the list is prepared only once (it can be a bit time-consuming in case of many unreachable repos)

EDIT: One thing which is left is to comment the unit tests, but the rest is ready for review.

[danmyway]

/packit test --labels tier0

[danmyway]

/packit retest-failed

[danmyway]

/packit test --labels tier0

[has-bot]

/packit test --labels tier0

---

Comment generated by an automation.

Log | Bot Usage

[danmyway]

The failure of /tests/integration/tier1/destructive/system-not-up-to-date/system_not_updated is a false negative and to be fixed in #1423

[danmyway]

/packit test --labels tier0

[bocekm]

Not a problem coming with this PR (it's been like that for quite a while) but just for the record - there's a corner case where:

• the user has Satellite with the standard RHEL repos and some custom repo not starting with rhel that they want to use for the conversion (e.g. my-kernel-rebuild)
• they register their CentOS Linux 7 system to the Satellite and run convert2rhel --enablerepo=my-kernel-rebuild
• the repo is not disabled during checks such as the latest kernel check because the --no-rhsm option is not used => the check would provide invalid output

[hosekadam]

/packit test --labels tier0