Get rid of duplicated file names in spec tests

Otherwise, corresponding IDE tests would fail on creation duplicated
files in the same directory

compiler/tests-spec/testData/diagnostics/linked/expressions/try-expression/p-8/neg/1.1.kt

@@ -12,7 +12,7 @@
  * DESCRIPTION: The type of the try-expression is the least upper bound of the types of the last expressions of the try body and the last expressions of all the catch blocks
  */
 
-// FILE: TestCase.kt
+// FILE: TestCase1.kt
 // TESTCASE NUMBER: 1
 package testPackCase1
 
@@ -38,7 +38,7 @@ fun case1() {
     }
 }
 
-// FILE: TestCase.kt
+// FILE: TestCase2.kt
 // TESTCASE NUMBER: 2
 package testPackCase2
 
@@ -66,7 +66,7 @@ fun case2() {
 }
 
 
-// FILE: TestCase.kt
+// FILE: TestCase3.kt
 // TESTCASE NUMBER: 3
 // ISSUES: KT-35494
 package testPackCase3