[LiveDebugValues] Terminate open ranges on DBG_VALUE $noreg

In D68209, LiveDebugValues::transferDebugValue had a call to
OpenRanges.erase shifted, and by accident this led to a code path where
DBG_VALUEs of $noreg would not have their open range terminated, allowing
variable locations to extend past blocks where they were terminated.

This patch correctly terminates the open range, if present, when such a
DBG_VAUE is encountered, and adds a test for this behaviour.

Differential Revision: https://reviews.llvm.org/D78218