Don't inherit parent Minimum Level for inline sublogger configuration

[skomis-mm]

What issue does this PR address?
Fixes #1346 , #1453

Does this PR introduce a breaking change?
Behavior change for subloggers configured inline when no explicit default level specified for them.

Please check if the PR fulfills these requirements

• The commit follows our guidelines
• Unit Tests for the changes have been added (for bug fixes / features)

Other information
Inheriting minimum level was done before overrides where introduced, so it doesn't take them into account now for subloggers which results in counterintuitive behavior.

[nblumhardt]

Since _applyInheritedConfiguration ends up calling:

        void ApplyInheritedConfiguration(LoggerConfiguration child)
        {
            if (_levelSwitch != null)
                child.MinimumLevel.ControlledBy(_levelSwitch);
            else
                child.MinimumLevel.Is(_minimumLevel);
        }

it seems like removing that call here might be a cleaner fix?

I had a quick attempt at figuring out the original purpose of _applyInheritedConfiguration and can't track it down; I suspect it may have been part of an earlier version that took advantage of Logger directly implementing ILogEventSink.Emit() (without any level check), but can't immediately tell from the source.

Removing it entirely seems not to break any tests. Am I missing anything?

[skomis-mm]

I've tracked it down to this pr. Part of it was the fix for 804 issue.

The issue was about case with default minimum level of the root less than Information which results in explicit setting minimum for subloggers by users.

The open question - why it was choosen the same as for the parent instead of Verbose..

Hint about Logger as ILogEventSink led me to examples:

Behavior before this pr:

new LoggerConfiguration()
    .MinimumLevel.Verbose()
    .WriteTo.Sink(
        new LoggerConfiguration()
            .MinimumLevel.Fatal()
            .WriteTo.Console()
            .CreateLogger())
    .CreateLogger()
    .Verbose("oops"); // surpasse the Fatal filter

but

new LoggerConfiguration()
    .MinimumLevel.Verbose()
    .WriteTo.Sink(
        new LoggerConfiguration()
            .MinimumLevel.Fatal()
            .WriteTo.Logger(lc => lc.WriteTo.Console())
            .CreateLogger())
    .CreateLogger()
    .Verbose("oops"); // suppressed by the sublogger's Fatal filter

After this pr both examples will result in surpassing the Fatal filter. And makes the behavior consistent :)

So it makes sense to remove these lines as you pointed.

[nblumhardt]

Sorry I missed your mention/comments on 1453 - I've kept meaning to loop back around to this 😓

Making some time to catch up, now.

[skomis-mm]

Removed ApplyInheritedConfiguration since it was used just in one place

[nblumhardt]

LGTM 👍