Need a complete fix for broken `GetUserByName`

[wxiaoguang]

See #24026 (comment)

That change is wrong:

• Before GetUserByName can be used to get a org owner.
• After: it's expected that only Individual can be found.
  • But the new logic is also wrong, Individual is 0 then it takes no effect.
  • So the bug of bug makes the existing code still can use GetUserByName to find an org
  • But all other types can also be found by GetUserByName

Also, GetUserOrOrgByName is not right, no type check.

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And more related bugs:

• Users logs in as existing organization #36439

[wxiaoguang]

@techknowlogick @lunny

[lunny]

I will suggest we need to clarify what's the different between all these types' users before have some code.

Role Type	Can Login	Can be assigned issues	Can be assigned permissions	Can have projects or packages
Individual	Yes	Yes	Yes	Yes
Organization	No	No	No	Yes
xxx

Or we may need to temporarily disable all other types until we can clearly identify and clarify the differences between them.