Update CODEOWNERS paths: fix invalid paths and deprioritize /eng/ and Engineering System Team paths

[konrad-jamrozik]

As part of ongoing work of enabling wildcard support for CODEOWNERS:

• Add support for wildcard handling of file matching in codeowners library azure-sdk-tools#2770
• Enable the new, regex-based, wildcard-supporting CODEOWNERS matcher azure-sdk-tools#5088

and enabling stricter validation:

• Implement CODEOWNERS file changes validation (gating), with baselining azure-sdk-tools#4859

this PR:

• fixes invalid paths, to match rules explained here;
• deprioritizes ownership rules for /eng/ dir and Azure SDK Engineering System team , to avoid all build failure notifications being routed to it once we enable the new regex-based, wildcard-supporting CODEOWNERS matcher, per: Enable the new, regex-based, wildcard-supporting CODEOWNERS matcher azure-sdk-tools#5088 (comment)

As a consequence of this PR possibly the automatically assigned PR reviewers will change for some paths. The full list of of such changes can be determined by running relevant test provided by this PR:

• Add manual tools for reporting information required to enable regex-based wildcard-supporting CODEOWNERS matcher on all remaining repositories in scope. azure-sdk-tools#5266

You can also reach out to me to get that information.

Once this PR is merged, I will enable the new CODEOWNERS matcher, similar to how it was done for net repo by these two PRs:

• Enable regex-based wildcard-supporting CODEOWNERS matcher for azure-sdk-for-net repo azure-sdk-tools#5241
• Update NotificationConfiguration package from 20230119.1 to 20230127.4 azure-sdk-tools#5240

Doing so will also change to whom build failure notification emails are sent.

Related PRs:

• Similar PR fixing invalid paths, but for net repo: Fix invalid paths in CODEOWNERS azure-sdk-for-net#33584
• Similar PR deprioritizing the Azure SDK EngSys team ownership, but for python repo: Deprioritize CODEOWNERS EngSys ownership + fix one invalid path azure-sdk-for-python#28534

Build failure notification recipients changes

For a build definition whose source is PATH, now its build failure notification recipients will be RIGHT OWNERS, while previously they where LEFT OWNERS:

[konrad-jamrozik]

/check-enforcer override