sql: refactor update_view_references a bit

The function update_view_references is called when an SQL view
is created or dropped. The goal of this function is to modify
(increment or decrement) view_ref_count member of spaces that
the view references.

There were a several issues that deserves to be refactored:
* By design in case of error it left the job partially done, so
  some space references were modified while some other - not.
  Although there was no bug since special steps were made in case
  of error, this pattern is inconvenient and should be avoided.
* In case of error the failing space name was returned via special
  argument which is not flexible and even requires allocation.
* Another argument - suppress_error - has actually never
  suppressed any error because the only case when an error could
  occur is creation of a view, which used suppress_error = false.
* Fail of that function was not actually covered with tests.

So this commit:
* Makes the function to do all or nothing.
* Forces the function to set diag by itself in case of error.
* Removes suppress_error argument while adding several asserts.\
* Adds a small test that fulfills coverage.

NO_DOC=refactoring
NO_CHANGELOG=reafactoring