Elvis DFA: now only left part is taken into account #KT-9100 Fixed

I had to fix a few incorrect tests using something like x!! in Elvis right part, and also one bug in our code

compiler/testData/diagnostics/tests/smartCasts/elvisExclExclMerge.kt

@@ -0,0 +1,6 @@
+fun test(x: Any?): Any {
+    val z = x ?: x!!
+    // x is not null in both branches
+    <!DEBUG_INFO_SMARTCAST!>x<!>.hashCode()
+    return z
+}