CNDB-16289: switch index hints limit to use Short.MAX_VALUE (#2174)

### What is the issue

Currently `maxIncludedOrExcludedIndexCount` is using
`getSecondaryIndexesPerTableFailThreshold` but the coordinator will
always validate that the indexes mentioned by the index hints exist in
the schema, and there cannot be repeated index in the hints because the
hints are disjoint sets. So the number of index hints is implicitly
limited by the number of existing indexes, therefore we should use
Short.MAX_VALUE like main does.

### What does this PR fix and why was it fixed

Change the index hint limit to use Short.MAX_VALUE

Author: driftx

src/java/org/apache/cassandra/db/filter/IndexHints.java

@@ -32,7 +32,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import org.apache.cassandra.config.DatabaseDescriptor;
 import org.apache.cassandra.exceptions.UnknownIndexException;
 import org.apache.cassandra.cql3.QualifiedName;
 import org.apache.cassandra.db.TypeSizes;
@@ -62,8 +61,7 @@ public class IndexHints
     public static final String WRONG_KEYSPACE_ERROR = "Index %s is not in the same keyspace as the queried table.";
     public static final String MISSING_INDEX_ERROR = "Table %s doesn't have an index named %s";
     public static final String NON_INCLUDABLE_INDEXES_ERROR = "It's not possible to use all the specified included indexes with this query.";
-    // The limit is determined by maxIncludedOrExcludedIndexCount() which uses the guardrail or 128 by default
-    public static final String TOO_MANY_INDEXES_ERROR = "Exceeded the maximum number of included/excluded indexes. Found ";
+    public static final String TOO_MANY_INDEXES_ERROR = format("Cannot have more than %d included/excluded indexes, found ", Short.MAX_VALUE);
 
     public static final IndexHints NONE = new IndexHints(Collections.emptySet(), Collections.emptySet())
     {
@@ -386,10 +384,10 @@ public static IndexHints fromCQLNames(Set<QualifiedName> included,
                                           TableMetadata table,
                                           IndexRegistry indexRegistry)
     {
-        if (included != null && included.size() > maxIncludedOrExcludedIndexCount())
+        if (included != null && included.size() > Short.MAX_VALUE)
             throw new InvalidRequestException(TOO_MANY_INDEXES_ERROR + included.size());
 
-        if (excluded != null && excluded.size() > maxIncludedOrExcludedIndexCount())
+        if (excluded != null && excluded.size() > Short.MAX_VALUE)
             throw new InvalidRequestException(TOO_MANY_INDEXES_ERROR + excluded.size());
 
         IndexHints hints = IndexHints.create(fetchIndexes(included, table, indexRegistry),
@@ -415,14 +413,6 @@ public static IndexHints fromCQLNames(Set<QualifiedName> included,
         return hints;
     }
 
-    private static int maxIncludedOrExcludedIndexCount()
-    {
-        int guardrail = DatabaseDescriptor.getGuardrailsConfig().getSecondaryIndexesPerTableFailThreshold();
-
-        // If no guardrail is configured, use a value that safely fits in a single byte for serialization:
-        return guardrail > 0 ? guardrail : 128;
-    }
-
     private static Set<IndexMetadata> fetchIndexes(Set<QualifiedName> indexNames, TableMetadata table, IndexRegistry indexRegistry)
     {
         if (indexNames == null || indexNames.isEmpty())
@@ -598,7 +588,7 @@ private void serialize(Set<IndexMetadata> indexes, DataOutputPlus out, int versi
                 return;
 
             int n = indexes.size();
-            assert n <= maxIncludedOrExcludedIndexCount() : TOO_MANY_INDEXES_ERROR + n;
+            assert n < Short.MAX_VALUE : TOO_MANY_INDEXES_ERROR + n;
 
             out.writeVInt32(n);
             for (IndexMetadata index : indexes)