Fix bugs in loading code from yaml

[masci]

Related Issue(s): no issue, addressing failing tests on master

Proposed changes:

• Stop relying on .endswith to determine if the instance is a leaf of the hierarchy tree. That check would mistakenly consider BaseElasticsearchDocumentstore.__init__ be the same as ElasticsearchDocumentstore.__init__. We now manipulate and compare the actual tokens composing the fully qualified name of a __init__ method.
• Do not store constructor's parameters for the ancestors of a node instance we want to save/load. This was supposed to fail but thanks to the bug from the point above continued working
• Remove the function _get_signature that was used to recursively collect all the params for all the constructors calls chain, the code isn't used anymore.

Pre-flight checklist

• I have read the contributors guidelines
• I have enabled actions on my fork
• If this is a code change, I added tests or updated existing ones
• If this is a code change, I updated the docstrings

[tstadel]

@masci Nice catch regarding the .endswith bug. Once the tests run through I'll approve.

[tstadel]

@masci btw why did the md file of this tutorial get updated? Was there a merge before without running the Code & Documentation Updates job correctly?

[masci]

@masci btw why did the md file of this tutorial get updated? Was there a merge before without running the Code & Documentation Updates job correctly?

I have no idea but I'm not very happy about the bot cluttering my PR :/

[ZanSara]

Weird! The changes come from this PR probably, where it seems like the bot was working fine... We should really do something about this 😅

[ZanSara]

Please merge master after we merge in #2714, so the bot will stop spamming 😅

[tstadel]

LGTM!