[FIR] Disambiguate names of files with helpers in spec tests

Test framework assumes that there won't be any files with same names
  in one test. But there were cases when test declared test file
  with same name as one of files with helpers (e.g. `functions.kt`)

compiler/tests-spec/testData/diagnostics/linked/expressions/constant-literals/the-types-for-integer-literals/p-1/neg/2.5.fir.kt

@@ -1,7 +1,6 @@
-// FIR_DISABLE_LAZY_RESOLVE_CHECKS
 // SKIP_TXT
 
-// FILE: functions.kt
+// FILE: testFunctions.kt
 
 package functions
 

compiler/tests-spec/testData/diagnostics/linked/expressions/constant-literals/the-types-for-integer-literals/p-1/neg/2.5.kt

@@ -1,4 +1,3 @@
-// FIR_DISABLE_LAZY_RESOLVE_CHECKS
 // FIR_IDE_IGNORE
 // SKIP_TXT
 
@@ -12,7 +11,7 @@
  * HELPERS: checkType
  */
 
-// FILE: functions.kt
+// FILE: testFunctions.kt
 
 package functions