Fix air config (#6655)

Since backend process does not treat SIGINT, removed `send_interrupt` config from `./.air.toml`.
Otherwise backend process remains as zombie.

Author: shu-mutou

.air.toml

@@ -15,7 +15,6 @@ tmp_dir = ".tmp"
   include_ext = ["go"]
   kill_delay = "1s"
   log = "build-errors.log"
-  send_interrupt = true
   stop_on_error = true
 
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