Drop all tests that disable features for language version less than 3

compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureOff.fir.kt

@@ -1,15 +0,0 @@
-// !LANGUAGE: -CapturedInClosureSmartCasts
-
-fun run(f: () -> Unit) = f()
-
-fun foo(s: String?) {
-    var x: String? = null
-    if (s != null) {
-        x = s
-    }
-    if (x != null) {
-        run {
-            x.hashCode()
-        }
-    }
-}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureOff.kt

@@ -1,15 +0,0 @@
-// !LANGUAGE: -CapturedInClosureSmartCasts
-
-fun run(f: () -> Unit) = f()
-
-fun foo(s: String?) {
-    var x: String? = null
-    if (s != null) {
-        x = s
-    }
-    if (x != null) {
-        run {
-            <!SMARTCAST_IMPOSSIBLE!>x<!>.hashCode()
-        }
-    }
-}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureOff.txt

@@ -1,4 +0,0 @@
-package
-
-public fun foo(/*0*/ s: kotlin.String?): kotlin.Unit
-public fun run(/*0*/ f: () -> kotlin.Unit): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryUnsound.fir.kt

@@ -1,10 +0,0 @@
-// !LANGUAGE: -SoundSmartCastsAfterTry
-
-fun foo() {
-    var s: String?
-    s = "Test"
-    try {
-        s = null
-    } catch (ex: Exception) {}
-    s<!UNSAFE_CALL!>.<!>hashCode()
-}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryUnsound.kt

@@ -1,10 +0,0 @@
-// !LANGUAGE: -SoundSmartCastsAfterTry
-
-fun foo() {
-    var s: String?
-    s = "Test"
-    try {
-        s = null
-    } catch (ex: Exception) {}
-    <!DEBUG_INFO_SMARTCAST!>s<!>.hashCode()
-}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryUnsound.txt

@@ -1,3 +0,0 @@
-package
-
-public fun foo(): kotlin.Unit