[LL] do not build fir in a non-cancelable section

find by classId might require indices which will throw PCE when not up-to-date
which is prohibited in non-cancelable section

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/util/declarationUtils.kt

@@ -117,9 +117,7 @@ var KtFile.originalKtFile by UserDataProperty(ORIGINAL_KT_FILE_KEY)
 
 private fun KtClassLikeDeclaration.findFir(provider: FirProvider): FirClassLikeDeclaration? {
     val classId = getClassId() ?: return null
-    return executeWithoutPCE {
-        provider.getFirClassifierByFqName(classId) as? FirRegularClass
-    }
+    return provider.getFirClassifierByFqName(classId) as? FirRegularClass
 }