github: automation: fixed rules for commit scope check

[vpirogov]

This PR updates commit checker to avoid false positives in #2279 (job link), #2276, and #2272.

As : can be used in commit message itself there's no good way to reliably identify cases with multi-level scope.

[theComputeKid]

This means that e.g. Removing: from doc would be a valid commit title, since there is no validation of the initial tag.

[vpirogov]

This means that e.g. Removing: from doc would be a valid commit title, since there is no validation of the initial tag.

No, this one will fails because of capital 'R' :). Anything that follows the format of <scope>: <description> or <scope1>, <scope2>: <description> will fly. Testing on commits since oneDNN v3.5 release indicates that nothing really ugly passes and less than 3% of commits fail.