Get rid of the unnecessary permissions for implicit domains

[dyemanov]

This PR addresses some issues spotted in #8881:

1. Dropping a field / parameter which is based on implicit domain leaves orphan records inside RDB$USER_PRIVILEGES and RDB$SECURITY_CLASSES
2. No privileges should be assigned to implicit domains created under the hood

[aafemt]

While you are at it, could you also mark implicit domains as system, please?..

[dyemanov]

While you are at it, could you also mark implicit domains as system, please?..

I'm not sure this is correct (and that it will not cause backward compatibility issues).

[aafemt]

But it would allow to clean out the hack with RDB$ prefix comparison from Firebird code and give users more freedom in domain naming.

[sim1984]

In my mind, a system domain is a domain that is used in system tables. You can add the automatically generated domain flag to ods 14.

[aafemt]

I always read it as "created and maintained by system" in contrast to "created by user".

[AlexPeshkoff]

Sorry that I did not mention it at once - in that case no reasons to have create parameter in executeAlterIndividualParameters, false is always passed to it.