DocValuesConsumerUtil tweak (elastic#132586)

Be more strict about not finding a metadata entry based on field info number.
If this were to happen, then this can cause issues in doc value consumer later.
An example of such a failure is what is fixed via elastic#132597, here with shrinking
the local segment and merged field numbers were not aligned causing serious
merge errors in the tsdb doc value consumer. Currently such an issue shouldn't
occur anymore.

Author: martijnvg

server/src/main/java/org/elasticsearch/index/codec/tsdb/es819/DocValuesConsumerUtil.java

@@ -64,20 +64,29 @@ static MergeStats compatibleWithOptimizedMerge(boolean optimizedMergeEnabled, Me
                             if (entry != null) {
                                 sumNumValues += entry.numValues;
                                 sumNumDocsWithField += entry.numDocsWithField;
+                            } else {
+                                assert false : "unexpectedly got no entry for field [" + fieldInfo.number + "\\" + fieldInfo.name + "]";
+                                return UNSUPPORTED;
                             }
                         }
                         case SORTED_NUMERIC -> {
                             var entry = tsdbDocValuesProducer.sortedNumerics.get(fieldInfo.number);
                             if (entry != null) {
                                 sumNumValues += entry.numValues;
                                 sumNumDocsWithField += entry.numDocsWithField;
+                            } else {
+                                assert false : "unexpectedly got no entry for field [" + fieldInfo.number + "\\" + fieldInfo.name + "]";
+                                return UNSUPPORTED;
                             }
                         }
                         case SORTED -> {
                             var entry = tsdbDocValuesProducer.sorted.get(fieldInfo.number);
                             if (entry != null) {
                                 sumNumValues += entry.ordsEntry.numValues;
                                 sumNumDocsWithField += entry.ordsEntry.numDocsWithField;
+                            } else {
+                                assert false : "unexpectedly got no entry for field [" + fieldInfo.number + "\\" + fieldInfo.name + "]";
+                                return UNSUPPORTED;
                             }
                         }
                         case SORTED_SET -> {
@@ -90,6 +99,9 @@ static MergeStats compatibleWithOptimizedMerge(boolean optimizedMergeEnabled, Me
                                     sumNumValues += entry.ordsEntry.numValues;
                                     sumNumDocsWithField += entry.ordsEntry.numDocsWithField;
                                 }
+                            } else {
+                                assert false : "unexpectedly got no entry for field [" + fieldInfo.number + "\\" + fieldInfo.name + "]";
+                                return UNSUPPORTED;
                             }
                         }
                         case BINARY -> {
@@ -98,6 +110,9 @@ static MergeStats compatibleWithOptimizedMerge(boolean optimizedMergeEnabled, Me
                                 sumNumDocsWithField += entry.numDocsWithField;
                                 minLength = Math.min(minLength, entry.minLength);
                                 maxLength = Math.max(maxLength, entry.maxLength);
+                            } else {
+                                assert false : "unexpectedly got no entry for field [" + fieldInfo.number + "\\" + fieldInfo.name + "]";
+                                return UNSUPPORTED;
                             }
                         }
                         default -> throw new IllegalStateException("unexpected doc values producer type: " + fieldInfo.getDocValuesType());