fuzz: Reduce LIMITED_WHILE limit for file fuzzing

A higher limit is not needed, and only leads to timeouts, see for
example the buffered_file one in
https://github.com/bitcoin/bitcoin/issues/28812#issue-1981386486

src/test/fuzz/autofile.cpp

@@ -21,7 +21,8 @@ FUZZ_TARGET(autofile)
     AutoFile auto_file{
         fuzzed_file_provider.open(),
     };
-    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000) {
+    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 100)
+    {
         CallOneOf(
             fuzzed_data_provider,
             [&] {

src/test/fuzz/buffered_file.cpp

@@ -26,7 +26,8 @@ FUZZ_TARGET(buffered_file)
     }
     if (opt_buffered_file && !fuzzed_file.IsNull()) {
         bool setpos_fail = false;
-        LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000) {
+        LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 100)
+        {
             CallOneOf(
                 fuzzed_data_provider,
                 [&] {