Signal m_tip_block_cv when Ctrl-C is pressed or SIGTERM is received, the same
way it is currently signalled when the `stop` RPC is called. This lets RPC
calls like `waitforblockheight` and IPC calls like `waitTipChanged` be
interrupted, instead of waiting for their original timeouts and delaying
shutdown.
Historical notes:
- The behavior where `stop` RPC signals `m_tip_block_cv`, but CTRL-C does not,
has been around since the condition variable was introduced in #30409
(7eccdaf160).
- The signaling was later moved without changing behavior in #30967
(5ca28ef28b). This commit moves it again to
the Interrupt() function, which is probably the place it should have been
added initially, so it works for Ctrl-C shutdowns as well as `stop`
shutdowns.
- A Qt shutdown bug calling wait methods was fixed previously in #18452
(da73f1513a), and this change updates that
fix to avoid the hang happening again in Qt.
Github-Pull: #33511
Rebased-From: c25a5e670b
c065bcd2d7