FIR CFG: correct edge label from a node that returns Nothing

If it's not within a try/catch/finally, that should be an uncaught
exception path.

^KT-45327 Fixed

compiler/testData/diagnostics/testsWithStdLib/exitProcess.fir.kt

@@ -1,14 +0,0 @@
-import java.io.File
-import kotlin.system.exitProcess
-
-object Main {
-    <!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>private val KOTLIN_HOME: File<!>
-
-    init {
-        val home = System.getProperty("kotlin.home")
-        if (home == null) {
-            exitProcess(1)
-        }
-        KOTLIN_HOME = File(home)
-    }
-}

compiler/testData/diagnostics/testsWithStdLib/exitProcess.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 import java.io.File
 import kotlin.system.exitProcess