Update pattern for finding diagnostics in diagnostic tests

Also use updated diagnostic pattern in TreesCompareTest.
In rare cases diagnostic was cut too early on !> characters,
that were a part of diagnostic parameter:
<!DIAGNOSTIC("Type<DefinitelyNotNullTypeArgument!!>")!>

compiler/fir/lightTree/tests/org/jetbrains/kotlin/fir/lightTree/compare/TreesCompareTest.kt

@@ -10,6 +10,7 @@ import com.intellij.openapi.vfs.CharsetToolkit
 import com.intellij.testFramework.TestDataPath
 import com.intellij.util.PathUtil
 import junit.framework.TestCase
+import org.jetbrains.kotlin.checkers.BaseDiagnosticsTest.Companion.DIAGNOSTIC_IN_TESTDATA_PATTERN
 import org.jetbrains.kotlin.fir.FirRenderer
 import org.jetbrains.kotlin.fir.builder.AbstractRawFirBuilderTestCase
 import org.jetbrains.kotlin.fir.builder.StubFirScopeProvider
@@ -77,7 +78,7 @@ class TreesCompareTest : AbstractRawFirBuilderTestCase() {
                 return@compareBase true
             }
             val notEditedText = FileUtil.loadFile(file, CharsetToolkit.UTF8, true).trim()
-            val text = notEditedText.replace("(<!>)|(<!.*?!>)".toRegex(), "").replaceAfter(".java", "")
+            val text = notEditedText.replace(DIAGNOSTIC_IN_TESTDATA_PATTERN, "").replaceAfter(".java", "")
 
             //psi
             val ktFile = createPsiFile(FileUtil.getNameWithoutExtension(PathUtil.getFileName(file.path)), text) as KtFile