test: fix metaedit tests by forcing dates Mercurial < 4.3 don't have default date so restore aliases forcing date in the test-metaedit.t file.

test: split test-stablesort.t in two This is the longest running test so we split it in two to help with parallel execution.

obsdiscovery: automatically pick protocol in a list This makes the code cleaner, clearer and more flexible. This also prepare the ability to disable obsmarkers discover entirely.

obsdiscovery: extract push-obshashtree discovery in a function This will help use to simplify the code.