Replace Failure._findFailure dependency on bytecode with some mechanism that doesn't rely on bytecode

[itamarst]

The problem:

• As seen in Fix inlineCallbacks tests on Python 3.13 #12061, changes to generated bytecode can break Failure's special inlineCallbacks related code(and quite possibly async functions too).
• In a world where a CPython JIT is a possibility, it's not clear if any of this will work at all in the future.

It would be better to have a mechanism for finding the current failure that is less tied to obscure implementation details of Python. Perhaps contextvars might do the trick?

[itamarst]

😱 that is all

[itamarst]

Notes for the PR:

• It also fixes Fix inlineCallbacks tests on Python 3.13 #12061 and Stop calling Failure.cleanFailure() in Deferred error handling #12234.
• This doesn't yet use use Python's nicer traceback printing (column indicators), mostly to keep the PR limited. Use Python's traceback printer, in order to get nice columns #12289 is the followup to do so.

[glyph]

@itamarst uhhh; presumably you meant something other than #12016?

[itamarst]

Yep, updated.