[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/secondaryConstructors/kt6993.fir.kt

@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+class X<T>(val t: T) {
+    constructor(t: T, i: Int) : this(i)
+}