[mlir] Fix use-after-move issues (#165660)
This patch addresses two use-after-move issues:
1. `Timing.cpp` A variable was std::moved and then immediately passed to
an `assert()` check. Since the moved-from state made the assertion
condition trivially true, the check was effectively useless. The
`assert()` is removed.
2. `Query.cpp` The `matcher` object was moved-from and then subsequently
used as if it still retained valid state. The fix ensures no subsequent
use for the moved-from variable.
Testing:
`ninja check-mlir`
