Drop unnecessary parameter in mysqlnd_auth

[kamil-tekiela]

The PR changes the signatures of methods in mysqlnd_auth to remove the session_options parameter which is just a shortcut for conn->options. Since conn is available in all of these method signatures, it doesn't make much sense to duplicate the information.

[bukka]

What's the point of this?

[kamil-tekiela]

Code cleanup.

[TimWolla]

It's hard to tell the impact based from the diff, commit messages and PR description alone. It doesn't entirely look like a noop, but I'm not familiar with this part of the code.

Either way, please add an entry to UPGRADING.INTERNALS, explaining that the change was made and what actions a developer needs to take of they happen to use the removed API.

[kamil-tekiela]

I have added an UPGRADING entry and I have split it up into two PRs for better clarity. #20979

[TimWolla]

Thanks for the explanation, this makes sense to me then. Please wait a little for others to check and agree with the removal before merging.

[bukka]

This one is now fine. Don't think it even needs note in UPGRADING internals because it does not change any exported as far as I see.