deprecate passing extension option to sanity_check_step & sanity_check_load_module methods in EasyBlock class

[Flamefire]

This removes the superflous parameter which is always set to self.extension anyway.
It looks like an artifact from when that member didn't exist or was not set consistently.

I did this in a PR prior to the 5.3.0 release but took out to get that PR merged without this change.
Reason is to avoid potential mismatches, e.g. by forgetting to pass the parameter.
Ultimately I want to use self.is_extension to allow multiple extension to fail their sanity check step and having a "parallel" source of truth makes that harder.
The cause here is that the failing exts_filter allows to check other extensions but failing commands does not as that aborts directly. Easy to fix when relying on self.is_extension

I'll also removed it from sanity_check_load_module which is similarly simple but requires an update to the easyblocks that use it.

[boegel]

shouldn't this still check self.extension?

Suggested change

	if build_option('sanity_check_only'):
	if build_option('sanity_check_only') and not self.extension:

[boegel]

ah, no, because of the inline return above...

[boegel]

Looks OK to me.

I dug into the history a bit:

• self.is_extension was first introduced in e68bc97 (Jan'13, EasyBuild v1.11.0), but only in ExtensionEasyBlock class, so it could not be used generally;
• later, in 85f17b6 (Mar'19, EasyBuild v3.9.0), a change was made to ensure that self.is_extension is always defined in EasyBlock class, so since then we can always rely on it, but by then we had the extension option is various methods to effectively pass down the is_extension class parameter

So, makes sense to me to clean this up as proposed.

[boegel]

lgtm