test(suites): Take the copy only once the paste has settled
audit_webhook took the X clipboard as soon as the collector had the
paste, where the Python suite gave the paste 1.5 s. The server's write
of the paste comes back to its clipboard monitor as a selection
change, and the monitor announces a change it handles once another
client owns the selection as that client's copy: handled after the copy
was taken, the paste's change announced the copy a second time, and CI
counted three sends of it for two (run 43553724941; the other 19 Rust
suites passed there).
The copy is taken 1.5 s after the paste again, as the Python suite took
it: nothing reports when the monitor has handled the paste's change.